First gen blazer swap

[Rab38]

I am looking to put a duramax in my 72 k5. I am trying to decide on what automatic trans to go with. I don't believe the Allison will fit due to the length. The truck is lifted so I need to keep the drive train as short as possible for drive shaft angles.

I think the best choices are either a duraflte or a 4r100? Does any one have the length of these two transmissions? I need to find that out so I can see how much longer it is compared to the turbo 350. My plan is to move the engine forward as much as possible to offset the additional length.

I plan to either run my 205 transfer case or step up to an atlas.

Any advice is appreciated.
Thanks

 

[catman3126]

Theres a good thread on here with a guy doing the same thing but he put the duramax frame under the blazer. ill see if i can find it.

 

[Rab38]

I saw that but I want to use my factory frame. I don't want to lose the factory look. I will box the frame and probably tie in my roll cage to the front clip area to help handle the torque

 

[Mike L.]

I don't think the Duramax engine will clear the front diff on a stock frame on the early Blazer.

 

[Rab38]

The truck is lifted considerably so I don't believe that I will have issues there. Is the oil pan deeper then say a big block oil pan?

 

[THEFERMANATOR]

The truck is lifted considerably so I don't believe that I will have issues there. Is the oil pan deeper then say a big block oil pan?

Yes, a good 2 inches or so I would say as well as extending furthur forward.

 

[Rab38]

Well that should not be an issue, I have significant clearance with my lift. I talked to suncoast about different transmissions and they said the Allison is 30" long I just need to change my input shaft to a 29 spline. The 4r100 is longer and they seemed to steer me away from a duraflite.

I believe my t350 is only 22" long, I have about 6" of room I can move the engine forward in the bay with the current 383. I am running electric fans.

Need to figure out what the overall length is on the duramax and Allison mated together to see how hard this is going to be.

 

[chevyburnout1]

What about moving the radiators? Would that get you any more room? Maybe two small radiators mounted horizontally under each floorboard? The only reason I think of that is the shop I work at built a 69 Bronco with a rear-mounted turbo feeding a built 428. They put all the coolers under the floor on each side with electric fans.

 

[Rab38]

I found an 06 duramax out of a van but it is 2wd. So will there be an issue with converting to a 4wd Trans? Is the Trans computer different between a 2wd and a 4wd? Thanks

 

[BlackHillsHD]

The van transmission will not be an Allison.

 

[Rab38]

It's a 4l85 correct? Any issues with the computer being from a 2wd truck and running a 4wd trans?

 

[BlackHillsHD]

Yes. Only issue that I see is if you change it to 4x4, you might run into some issues with the output speed sensor. But if you are going to run your 205 transfer case you can change your input to match.

 

[Rab38]

Yeah I was planning on using my 205 so the speed sensor will be mounted there.

 

[BlackHillsHD]

If you mount it on the output side of the transfer case you can have issues when using four low. It changes the ratio, and if the computer doesn't know it it can cause a limp mode.

 

[bcdeutsch731]

Here is my dads 72 we did. We were way to busy this summer at work and some bow my truck took up all are free time this summer to finish his truck. We're going to get it back in the shop this winter and finish it. I hope!! All that we need to do this winter is the turbo and intake piping and the whole interior.

That is the rear drive shaft. We're running 4x4 with the Allison trans.

 

[Big Block 88]

^^^^ Awsomeness

 

[MAXX IT OUT]

Are you planning running the 4l85e or swapping to truck transmission?

 

[Rab38]

I don't know yet. that is what I am trying to figure out now, what will work best for my application and what overdrive transmission will be the shortest so that I don't have issues with driveshaft angle.

 

[MAXX IT OUT]

I don't know yet. that is what I am trying to figure out now, what will work best for my application and what overdrive transmission will be the shortest so that I don't have issues with driveshaft angle.

If you decide your not going to use it and want to sell it, I would be intrested in it.

 

[THEFERMANATOR]

A 4L80E backed by a 241 transfer case with a slip yoke eliminator would be the shortest combo to run.