‘94 GMT400 Build

[EastAZfab]

Hey there! So to start off I just brought home this 1994 GMT 400. From the vin she started life as a 6.5 with 5 speed 4wd. Since then I’m not sure what the previous owners have done to it. Got mutiple stories and it had a 350 sitting in the engine bay chained up to a cherry picker when I found it. It’s a solid truck with a few rust spots the cab but over all pretty clean truck. I happen to have a donor 96 Tahoe with a running Vortec in it. The plan is to swap all the running Tahoe engine/computer/fuel lines/tank/wiring harnesses etc… ect and probably more ect.. I’ve done quite a bit of reading and research on the dash swaps/hvac computer/wiring differences. And I think I have a few good links for pin outs for all the electrical and even more right ups on the swap. But I was just sharing the build and will continue to update as things go along. Any pointers or tips/heads up greatly appreciated in advance!
~Long term goals either BBC or LS swap. Just going with what I got for now.

You must be registered for see images attach

You must be registered for see images attach

 

[Drunkcanuk]

Welcome from Alberta Canada.
That sounds like a LOT of work right off the hop if you are planning to go LS eventually. Not to poopoo on your plans, but you would probably be better off just doing an LS right off the hop. That way you don't have to do everything twice. Just my .02.
But either way, keep us posted, we love pics. And there is a wealth of knowledge and experience here as you probably already know.

 

[GrimsterGMC]

Welcome, I like the single cab look with dual wheels. Look forward to reading on your progress.

 

[Road Trip]

Welcome from the finger lakes region of NY. Don't know if you've had the chance
to look through some of the build threads, but it's great to watch when a member
takes another person's castoff and returns it to a 'Ready for Duty' status.

As for getting it running with what you've got, I for one think that it's preferable
to do this rather than to have the vehicle sit while waiting for all the perfect upgrade
bits to accrue. The first pass of getting it 90% to the goal will be plenty of work,
but after shaking out all the intermittents this way, when it comes time to make
the 2nd pass with the 'good stuff' you will be upgrading a 'known good' truck,
making it so much easier to get the whole enchilada over the finish line.

****

The only tip I have that surprises most new members is that there's
a fairly complete collection of the GMT400 Service Manuals that you can
download. (You're in luck, the '94 section looks to be complete.)

If you don't have them already, go HERE and set yourself up for success!

Rust free 3500HD with a stick -- there's a lot to like! Best of luck --

 

[EastAZfab]

You must be registered for see images attach

Finally got over the “this is gonna be a lot of work” mindset and tore into the Tahoe.

You must be registered for see images attach

And so it begins, I’m really wondering if this is the issue I’ve read about the 96-newer HVAC wiring issues this lovely connection was melted together. I opted to cut the HVAC side of the plug because prying at it for 20 minutes with no avail seemed pointless.

You must be registered for see images attach

So far so good in the engine bay. Been taking pictures with notes about what went where. Don’t have a pic of it but we have blue tape labeling the connections. I know there’s not much to it but it makes life a little simpler in the long run I think. As far as I’m in to this now. As far as putting all this in my ‘94. I know there are slight differences in HVAC controls I have a retro fit idea in mind to take the 96 controller and put it in the middle of the 94 dash where the aftermarket stereo might go. Seen a guy on here to a steel dash so something like that might be in progress. I’ve read that all the HVAC electrical has to swap over. The HVAC box stays the same but the blower motor, blend door motor, controls, ect all have to go together or the don’t work correctly. Spent more time in the engine bay today but I’ll post up more pics as I go along. Thanks.

 

[Komet]

I'd leave all the '94 HVAC in the '94 and just do what you have to do to trick the vortec ecm into running the motor.