Gaining 77+ rear seat leg room in a 73-75 K5, floor board mods, possible???

[blowedupmotor87]

My dad is thinking about getting a full convertible K5. I've never ridden in one but (IIRC), they have less rear seat leg room since the rear floor boards are at the same height as the cargo area, correct? I think it was '77 when they were dropped down to where they were in my '87? He really like the idea of a full convertible but, the (potentially) tight rear seat legroom makes him a little leery of it. I was wondering how hard it would be to modify the rear floor boards to give the legroom of the 77 plus??? I would think if it's possible, someone on here has likely done it but, I cannot find any info. (I've already looked at the thread of doing the full 'vert conversion on a later model but, that is likely not a potential prospect for two reasons- 1)no donor- haven't seen a 73-75 rough enough to feel right chopping it up just to get the top half of the windshield frame and the full hard top 3)he wants a pre '80 anyway (no inspection here due to being 35+ years old) and likes the frontend of the earlier K5's better so, the only thing gained by chopping the top off a half cab Blazer (and grafting over the full 'vert parts) would be the rear seat legroom) At that point, it seems like it would be more feasible just to modify the rear footwell area of the 73-75. OR, is it a more difficult proposition than I am imagining??? (like, are the frames different, preventing this from being done???)

 

[76k5blazerr]

It was 78 when GM switched to the new floor design. The 77 and earlier k5s legroom in the back really isn't all that bad. I'm 6'2 and can sit confortably in the backseat of my 76 blazer. The trick if you want a little more legroom is to just move the seat back a couple inches. Drill new holes in the bed floor and remount it, a few inches back. Who's gonna be riding in the backseat? If it's kids, I would leave it just how it is. Adults, maybe back the seat up a bit but I don't think I would want to mess with the hassle of trying to remake the floor to be like the 78 and up Blazers. I may be wrong but I am pretty sure the frames are slightly different.

 

[blowedupmotor87]

It was 78 when GM switched to the new floor design. The 77 and earlier k5s legroom in the back really isn't all that bad. I'm 6'2 and can sit confortably in the backseat of my 76 blazer. The trick if you want a little more legroom is to just move the seat back a couple inches. Drill new holes in the bed floor and remount it, a few inches back. Who's gonna be riding in the backseat? If it's kids, I would leave it just how it is. Adults, maybe back the seat up a bit but I don't think I would want to mess with the hassle of trying to remake the floor to be like the 78 and up Blazers. I may be wrong but I am pretty sure the frames are slightly different.

My bad, 78! Thanks for the heads up on that! It'll be adults since the grandkids (my nieces) are really little (rearward facing car seat little) so, they won't be riding in it for quite some time! When it comes to moving the seat back, are the seatblets attached to the seat then??? (it has been a few years but, I think I recall my 87's belts were attached to the floor and moving the seat back would also requite moving the depressions for the rods to which it latched to be moved back too, are the earlier seats merely bolted to the floor? (rather than being a foldable latched setup?))

Oh, one issue I forgot to address is body rigidity, we can fix that potential issue without too much difficulty added since a rollcage is in the plans anyway.

 

[Phil513]

I had a '77, with the oldschool floorboards, and I drove adults in the back all over the place. San Diego to Rosarito and Ensenada and back, Anza Borrego desert. That sort of thing. Everybody seemed to do fine. Didn't remount seats or anything.

 

[76k5blazerr]

I had a '77, with the oldschool floorboards, and I drove adults in the back all over the place. San Diego to Rosarito and Ensenada and back, Anza Borrego desert. That sort of thing. Everybody seemed to do fine. Didn't remount seats or anything.

There's really a pretty good amount of legroom in the back of a 73-77.

 

[76k5blazerr]

There's really a pretty good amount of legroom in the back of a 73-77.

And I'm pretty sure the seatbelts bolt to the seats in these years. The newer ones did bolt to the floor though. My seatbelts are bolted to the seat, because when I got the truck It didn't have seatbelts in the back so I pulled some from a junkyard.

 

[muddermilitia]

The frame changes in 78 so you cant just change floor boards. The rear kick up was moved back in 78 to accomodate the footwell. Previous to the that, that kick up is farther forward and the middle body mount is inboard the frame rails (73-77) 78 and later, the middle body tub mounts are outboard of the frame.

This is why you could bolt a pickup truck cab right to a 73-77 k5 frame with no modifications, but with a 78 and later frame, you would have to make a rear cab crossmember

 

[76k5blazerr]

The frame changes in 78 so you cant just change floor boards. The rear kick up was moved back in 78 to accomodate the footwell. Previous to the that, that kick up is farther forward and the middle body mount is inboard the frame rails (73-77) 78 and later, the middle body tub mounts are outboard of the frame.

This is why you could bolt a pickup truck cab right to a 73-77 k5 frame with no modifications, but with a 78 and later frame, you would have to make a rear cab crossmember

Thats what I thought, thanks for clearing that up.

 

[82355]

I hate the leg room in the back seat of a 1973-1977 Blazer.

Martin

 

[blowedupmotor87]

Thanks for all the info y'all!!!! He has decided the rear legroom is more important and now he kinda likes the half cab better than the full convertibles now that he is looking at them more (initially he was all about a full convertible) so, now we just need to find him one!!!! It'd be cool if he gets one, we're contemplating kind of a joint build, him buying the K5 and then us using my K30's full drivetrain, some 37s I've got sitting around, and some other miscellaneous parts I've got.