73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: robzkool2 on July 28, 2008, 11:33:47 pm
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my 87 1/2ton 2wd originally came with a 305tbi & 700r4 trans combo.when i bought the truck it has a 305 carb/th350 combo from i'm told an 84 suburban.the carb iz a 600 holley.my th350 broke and i'm puttin' a 700r4 with torque converter back in.the salvage yard said it came from an 84 suburban.the speedo looks to have a wire connector instead of a cable on the tailshaft.and it has the white 4-pin connector on the left for -i guess- the lock-up.the 87 computer iz still in the truck but not hooked to the engine.should i just ignore the computer and set up the trans as a retrofit install or can i use my existing wires?can i use the th350 dipstik & tube on the 700r4?how much length will have to come off the driveshaft?it's already been shortened an inch & half for my axle-flip drop.
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your ECM would have originally controlled the 700R4 lock-up (TCC). Since you're not using the computer harness, stand alone will be best for the trans. As long as your trans has the internal provisions, you basically just need to run switched 12v power through a vacuum switch and brake cancel switch (junkyard, free or cheap) to the trans.
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Look here to make it lockup: http://www.73-87.com/7387garage/drivetrain/lockup.htm
You will probably need to shorten it about 1.5", but you need it in there to measure first.