1978 Frame Vs 1986 Frame Compatibility

[ZombieK5]

It looks like I will be getting back on the Forum soon since I'm going to start working on my K5 again. Fingers crossed I have everything else fixed in my rag tag fleet of rust buckets.

To recap, I have a 77 Blazer but purchased a 78 nearly rust free tub. The 78 tub will not fit without modification on my 77 frame. I have the opportunity to purchase a 1986 frame in near perfect condition. Does anybody know if the 78 body will fit on the 86 frame without modifications? I know the 78 frame is different than the 77 to make room for the back seat footwells. I was wondering if there were any other differences between 1978 and 1986 I need to be made aware of.

 

[imiceman44]

It looks like I will be getting back on the Forum soon since I'm going to start working on my K5 again. Fingers crossed I have everything else fixed in my rag tag fleet of rust buckets.

To recap, I have a 77 Blazer but purchased a 78 nearly rust free tub. The 78 tub will not fit without modification on my 77 frame. I have the opportunity to purchase a 1986 frame in near perfect condition. Does anybody know if the 78 body will fit on the 86 frame without modifications? I know the 78 frame is different than the 77 to make room for the back seat footwells. I was wondering if there were any other differences between 1978 and 1986 I need to be made aware of.

I believe it's different where body mounts are but it would be easier to make work than the 77 in my opinion

 

[ZombieK5]

I believe it's different where body mounts are but it would be easier to make work than the 77 in my opinion

Any hints on which specific body body mounts? I I just welded a bunch of body mounts on a 2014 and 1990 Silverado. So, yes, that'd be easier

 

[imiceman44]

Any hints on which specific body body mounts? I I just welded a bunch of body mounts on a 2014 and 1990 Silverado. So, yes, that'd be easier

I don't know specifically but in the area of the back seat IIRC.
The frame goes wider in that area and that changed the mounts a bit.

 

[USSkoval]

Iirc, the mount locations changed for '78 and then stayed the same from then on. However, the mount bushings did change in '81. So you would need to use the '81+ bushings.

Bumper mounting also changed a little, but it's nothing that can't be worked around.

Oh yeah, I guess the mount locations did change slightly in '81... at the radiator support. It's off by 1/2" or so. Little bit of hole slotting can take care of that.

 

[ZombieK5]

Iirc, the mount locations changed for '78 and then stayed the same from then on. However, the mount bushings did change in '81. So you would need to use the '81+ bushings.

Bumper mounting also changed a little, but it's nothing that can't be worked around.

Oh yeah, I guess the mount locations did change slightly in '81... at the radiator support. It's off by 1/2" or so. Little bit of hole slotting can take care of that.

Can you define "off"

I can drill the hole out then weld in a piece to "move" the Hole. But...I'm confused. Don't the fenders and everything else interchange with all years? If the radiator support moved would the fender still work?

 

[USSkoval]

It's a difference in fore/aft placement. From what I remember, the '73-'80 rad support bushings are placed a little further rearward. So when using a '73-'80 front clip on an '81+ frame (no matter year of the cab) you need to slot the holes or use a different bushing. In my case, I used bushings from an '89 Celebrity engine cradle (had them laying around) which had enough wiggle room, that combined with the amount of adjustment in the rad support to fender attachments, it all bolted together ok.

Or you can cut the rivets and swap the mounts on the frame. But then you would need '73-'80 rad support bushings and '81+ body bushings.

Make sense?

 

[ZombieK5]

It's a difference in fore/aft placement. From what I remember, the '73-'80 rad support bushings are placed a little further rearward. So when using a '73-'80 front clip on an '81+ frame (no matter year of the cab) you need to slot the holes or use a different bushing. In my case, I used bushings from an '89 Celebrity engine cradle (had them laying around) which had enough wiggle room, that combined with the amount of adjustment in the rad support to fender attachments, it all bolted together ok.

Or you can cut the rivets and swap the mounts on the frame. But then you would need '73-'80 rad support bushings and '81+ body bushings.

Make sense?

Wow! Lots to digest..

 

[ZombieK5]

It's a difference in fore/aft placement. From what I remember, the '73-'80 rad support bushings are placed a little further rearward. So when using a '73-'80 front clip on an '81+ frame (no matter year of the cab) you need to slot the holes or use a different bushing. In my case, I used bushings from an '89 Celebrity engine cradle (had them laying around) which had enough wiggle room, that combined with the amount of adjustment in the rad support to fender attachments, it all bolted together ok.

Or you can cut the rivets and swap the mounts on the frame. But then you would need '73-'80 rad support bushings and '81+ body bushings.

Make sense?

Oh, to add to this. My 77 came with a 91+ radiator support. I did not take any notes about the bushings that supported it but I'm fairly certain they were Urethane aftermarket with a 3" lift plus a 1" aluminum puck. The rest of the truck I specifically remember had Urethane body bushings WITH 3" body lift (hard plastic bushings) AND 1" aluminum pucks.

I may do a 3" body lift but definitely not 4"

 

[ZombieK5]

Maybe good news.

Found a guy on a Squarebody Facebook page that has a 1978 FRAME and he put a 1986 BODY on it (kinda opposite my situ). He said he had ZERO fitment issues.

I just closed a deal for a cheap 86 frame in great shape. I get it this Sunday. My preliminary measurements show it should fit. More to follow

 

[ZombieK5]

Alright, rolling the dice. I just picked up this 86 frame that's supposedly will work with the 78 tub. I came across a guy who put a 86 tub on a 78 frame and he said it works flawlessly. If that's the case then my project should be fine. Hopefully this will go in the garage soon. I plan on having a sandblasted then primered and painted with either John Deere paint or Rust-Oleum Farm and Implement. Gonna be a fun summer.

 

[USSkoval]

One option that I like for frame "paint" is Slip Plate or EZ Slide. Different products, but basically the same. It's a graphite coating that can be rolled or brushed on.

 

[ZombieK5]

One option that I like for frame "paint" is Slip Plate or EZ Slide. Different products, but basically the same. It's a graphite coating that can be rolled or brushed on.

I've never even heard of that. Any links

 

[USSkoval]

I've never even heard of that. Any links

EZ-Slide Graphite Based Coating - 1 Gallon | eBay

EZ-Slide Graphite Based Coating - 1 Gallon 1 gal. Can EZ-Slide 9512 Series Graphite-Based Coating -Alkyd graphite-based lubricating paint that bonds quickly to most surfaces - Lead free. FRICTION SLIP CLUTCH DISC 5.50" OD X 3.00" ID.

ebay.us

It's available in aerosol as well, which is good for touch ups, but not great for covering a large area.

 

[ZombieK5]

EZ-Slide Graphite Based Coating - 1 Gallon | eBay

EZ-Slide Graphite Based Coating - 1 Gallon 1 gal. Can EZ-Slide 9512 Series Graphite-Based Coating -Alkyd graphite-based lubricating paint that bonds quickly to most surfaces - Lead free. FRICTION SLIP CLUTCH DISC 5.50" OD X 3.00" ID.

ebay.us

Primer first??

I'm planning to sand blast frame first then use a really good primer like the John Deere primer.

 

[Chickntrk]

EZ-Slide Graphite Based Coating - 1 Gallon | eBay

EZ-Slide Graphite Based Coating - 1 Gallon 1 gal. Can EZ-Slide 9512 Series Graphite-Based Coating -Alkyd graphite-based lubricating paint that bonds quickly to most surfaces - Lead free. FRICTION SLIP CLUTCH DISC 5.50" OD X 3.00" ID.

ebay.us

View attachment 524241

It's available in aerosol as well, which is good for touch ups, but not great for covering a large area.

Does this dry like paint? The description kinda makes it sound like it stays tacky like a wool wax product?

 

[USSkoval]

Primer first??

I'm planning to sand blast frame first then use a really good primer like the John Deere primer.

Does this dry like paint? The description kinda makes it sound like it stays tacky like a wool wax product?

It adheres very well to bare steel, and protects from rust as well. It cures and dries, and is relatively firm. Definitely not tacky or anything. Being a graphite product, it of course will transfer some amount of graphite to your finger if you were to run your finger on it a bunch.

I once considered painting an entire truck with it, but I'm betting it would not be fun to sand it all off for a proper paint job if it ever came to that. I may still do it anyway. The actual chances of painting it are slim to none.