TED'S 1972 K5 Build

[FRYE66]

We are new to this forum and interested in learning Blazer info and sharing what we do. We are presently in the process of doing a complete rebuild on a customer/friend's 1972 K5. I will post some pictures later, we have already stripped it completely. Actually Collin is media blasting the firewall and floor pans today. We have lower door pillar and floor patches and everything new from there down and back. Ted has went through the chassis, repairing crossmember and frame horn damage, powder coating everything possible. He has looked at the front and rear end/ brakes and repaired, painted etc. Going with a LS of some type and wondering about which transmission to use? The turbo 350 seems really solid but he will be doing quite a bit of interstate driving. with 33 possibly 35 tall tires and 3.73 gears. Any input on that?

 

[ashman]

If you're going with an ls swap, no reason not to go ahead and swap the tranny as well and get a computer controlled 4l60 that will give you overdrive.

 

[skunked]

35" tires, 4l60E, 4.56 or 4.88 gears

 

[FRYE66]

Yes, I think that combo would be best choice. But he's not wanting to replace the gears. Will it still cruise 75-80 with 3.73 and 33" or 35" tires, no OD?

 

[skunked]

Yes, I think that combo would be best choice. But he's not wanting to replace the gears. Will it still cruise 75-80 with 3.73 and 33" or 35" tires, no OD?

33's would probably be OK, it's a combo that many people are running with oversized tires on their Silverado's, Tahoe's etc.

 

[Greg72]

We are new to this forum and interested in learning Blazer info and sharing what we do. We are presently in the process of doing a complete rebuild on a customer/friend's 1972 K5. I will post some pictures later, we have already stripped it completely. Actually Collin is media blasting the firewall and floor pans today. We have lower door pillar and floor patches and everything new from there down and back. Ted has went through the chassis, repairing crossmember and frame horn damage, powder coating everything possible. He has looked at the front and rear end/ brakes and repaired, painted etc. Going with a LS of some type and wondering about which transmission to use? The turbo 350 seems really solid but he will be doing quite a bit of interstate driving. with 33 possibly 35 tall tires and 3.73 gears. Any input on that?

Welcome fellow 1st Gen owner!

Be sure to post photos..... this is the build section after all.


-G

 

[ekajkrats]

Yes, I think that combo would be best choice. But he's not wanting to replace the gears. Will it still cruise 75-80 with 3.73 and 33" or 35" tires, no OD?

I have 33's 3.07s and a th350 and highway driving is about all it's good for. My 33s are probably more like 31s so if driving on roads is all they want to do, I think their 35s or true 33s will be similar to my experience.

Now don't get me wrong, I go on easy trails and mild wheeling adventures and still have fun. But if I was going with all new drive train, you'd bet I'd switch to an OD transmission since I was was already down to bare frame. Finding already geared axles isn't too big an issue if you can afford to be patient.

I echo the sentiment of @skunked and @ashman. I also highly recommend reading over @ashman's thread for his ls swap. He did it about as inexpensively as possible.

-Jacob

 

[venevidivicci]

I have a 70 k5 that I started with a rebuilt 350, 350 combo and 4:10 gears on 33” tires. It drove me crazy trying to cruse on any kind of highway or freeway driving. I did a lot of research on converting to a 700r4 but without a core to trade in was looking at about $2200 just for the trans. I picked up a 5.3, 4l60e for $750 from a wrecked truck, advanced adapters kit to mate it to the stock 205 $250 at the time and bought HP tuners $500. No one made conversion motor mounts at the time so I used 2 plates with offset mounting patterns to mount the motor. That raised the motor so I dropped the engine crossmember to below the frame (you do not need a fancy engine crossmember for the 1st gen K5s) this cleared the stock oil pan for the 5.3l. So for $1500-$2000 it can be done very easily.

I am currently on 35” tires 4.10 gears 5.3l, 4l60e and NP205. I cruse at 85mph towing a pop up camper into the mountains every hunting season passing people all the way. I love this set up. Only wish I had a little bit lower gear in 4wd low for crawling. (Missed my chance at a lowmax 205 for $1000 and Kick myself for it.) otherwise a pretty perfect setup in my opinion.