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99 obs 3500 with lb7/Allison swap

A

Allday

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Hello. I’m working on a project that is probably a little different than what you guys are used to. It seems there are some knoledgable people on this forum so I’m hoping you guys can help me out with a few things. So we are doing an Lb7/Allison swap into a 99 3500 dually. The truck lays flat on the ground on milled down 24 inch semi wheels. The engine and trans are mounted up higher in the truck than normal since we are keeping the pans above the bottom of the frame. The engine and trans are mounted in the truck but I’m running into some issues that I need help on.

What shift linkage do I need to use the stock 99 column to shift the Allison trans

How are you guys able to cram the duramax radiator and inter cooler into these older trucks core support

Can I use the duramax Ac compressor with the factory 99 ac system.

I understand if you guys think the truck is useless or stupid. I understand most people don’t care for trucks like this. I’m mainly just looking for a little help on the swap. Thanks04835DBC-3444-4562-92CB-5BB1CFAAFBD7.jpeg3B670B9D-4FB6-4381-9282-E36439EB77D1.jpeg5C6D684A-EBBB-46DD-8B6F-2B9329640E2D.jpeg067D7A77-A6FD-46A5-ACD9-01585B33640D.jpegF9D36994-CAAF-4B2B-AA0E-358C6908A106.jpeg
 
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It hit me, why use the dmax radiator and inner cooler? Twisted Steel performance sells the improved aluminum radiator for these trucks, and he can do the thermal coating to it (rest of stack too if needed, I live Vegas and need my entire stack done for my hummer). Will cost a few bucks, but you could sell the factory units locally to make back some of it. bolt right in, will look and work great. The coating on the new aluminum one will basically improve it by 1/3 and the aluminum one will cool better than the stock.
twistedsteelperformance.com

Performance Ceramic coating

We are your one stop shop for High Performance Ceramic coatings and custom machining 864-362-6620
twistedsteelperformance.com
here it is without coating, but WAY WORTH IT imo.
twistedsteelperformance.com

Performance Ceramic coating

We are your one stop shop for High Performance Ceramic coatings and custom machining 864-362-6620
twistedsteelperformance.com

Also I know some guys fit the cummins inner cooler to the front of these trucks already (incase you cant fit the dmax one). I have one sitting in my garage because I was thinking about a project truck a few years back and grabbed one fairly cheap.
 
The duramax radiator(01-05) uses the same exact core as the 6.5l radiator does(34x19). Fitting the radiator isn't a problem, but the intercooler involves gutting the core support and doing some serious notching/clearancing to fit. By raising the engine you've created some issues. You're going to have to use a TALL cowl induction hood to clear the top of the engine. Mine is set as LOW as possible (I've got maybe 1/2" clearance between my oil pan and steering linkage) and I still rub the hood in several spots(intake tube, ac lines, and the bolts sticking up from the i take boot clamps). There's a very narrow spot where the engine/trans wants to set in this engine bay. You have to line the oil pan tunnel up with the steering linkage, the steering shaft up with the indent in the drivers side exhaust manifold, and if it's a 4x4 you have a SUPER narrow spot to squeeze in the transfer case between the cross-members. Since you're lowered so far with the powertrain raised so high, you're in uncharted territory.

As to ac, use the 01/02 style compressor(I will ONLY run a GPD brand compressor in this style) and the 6.5l hoses and such. You'll have to tweek a few bends in the vapor line, but it will fit. You may also want to join the duramax engine swap group on facebook as there is a few there who have done several of these.
 
THEFERMANATOR said:
The duramax radiator(01-05) uses the same exact core as the 6.5l radiator does(34x19). Fitting the radiator isn't a problem, but the intercooler involves gutting the core support and doing some serious notching/clearancing to fit. By raising the engine you've created some issues. You're going to have to use a TALL cowl induction hood to clear the top of the engine. Mine is set as LOW as possible (I've got maybe 1/2" clearance between my oil pan and steering linkage) and I still rub the hood in several spots(intake tube, ac lines, and the bolts sticking up from the i take boot clamps). There's a very narrow spot where the engine/trans wants to set in this engine bay. You have to line the oil pan tunnel up with the steering linkage, the steering shaft up with the indent in the drivers side exhaust manifold, and if it's a 4x4 you have a SUPER narrow spot to squeeze in the transfer case between the cross-members. Since you're lowered so far with the powertrain raised so high, you're in uncharted territory.

As to ac, use the 01/02 style compressor(I will ONLY run a GPD brand compressor in this style) and the 6.5l hoses and such. You'll have to tweek a few bends in the vapor line, but it will fit. You may also want to join the duramax engine swap group on facebook as there is a few there who have done several of these.
Click to expand...
Any idea on the shift cable. I’ve got the factory cable for the stock 4l80 and the Allison as well.
 
Nice! I had a slammed dully myself about 14 years ago traded it away for a Tahoe for my son.........who went on too blow 3 different 10 bolt rears in the Hoe a 14 bolt ff fixed that problem.

& WELCOME to the truck stop
 
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