nedfunnell

Hi,
I just bought an '82 GMC Sierra Classic 1500 with the 6.2L diesel V8. It's got high miles, but it was a fleet vehicle that was well taken care of with all maintenance. The bad news it that it's got zero highway miles- all the miles were put on over the course of 20 years of putting around a college campus.
Good news is that I paid $500 for it.
More bad news is that it has a 3-speed automatic, which replaced a 4-speed manual when it went out.
I'm going to keep the truck as a beater until I can afford to get a nice Cummins, but for now I want to swap out that transmission for something more highway-friendly. I've heard from friends that American made 80's trucks have interchangable transmissions, sometimes even between brands. Is this true? I also heard that transmissions from the next GMC generation (89) will bolt up also.
I'd be glad to find out that this is true. In short, though, I'm looking to find out what my options are for replacing the transmission, hopefully with a 4 or even 5-speed automatic. I'm not against manual, but it'll be much easier to go automatic to automatic than to go back to a manual.

Your input is appreciated!

wannadiesel

You will need a Chevy trans. The TH700-R4 was offered behind the 6.5 (big brother to the 6.2) so it would be a good swap. I don't think I'd bother, those trucks will do reasonable highway speeds without an overdrive trans. Don't sweat the mileage/hours. I worked for a bus company that had a Suburban of similar vintage that was their lot security/runaround vehicle. It had 225k on it when I left the company and had spent every night of its life idling around the yard. The engine had never been out of the truck, although it had the pump replaced a couple times.

gmctd

The 700R4 was offered behind the 6.2 from '82 to '93, in hydraulic and electric versions.

Uses the lockup torque convertor, same yoke as the T350 but shorter driveshaft

There's even a factory steering column with overdrive shift quadrant

catmandoo

i don't believe they were availible in 82 but my 83 suburban had one.too bad your not closer the sub rusted away to nothing so i junked it but still have the engine/trans.

nedfunnell

Where are you located, catmandoo? I'm going to be making a roadtrip in it(I hope) this winter up to the northeast.

Thanks for your input guys. Also, any ideas on what year ranges I should be looking for, or will anything with a 6.2 or 6.5 probably bolt right up? Thanks again!

derek840378

82 was the first year of the 6.2 and 700R4

nedfunnell

Thanks for the info, all. Does anyone know where I could find out which vehicles have the 700R4 transmission, and in what years? I'm pretty sure that this is something I can find pretty easily in a junkyard. How much should I expect to pay for a working 700R4 transmission? Thanks!

gmctd

Check any GM rear-wheel drive '82 to '90 for the hydraulic version, but the 6.2 had the D4 tc and full clutch packs, 6-gear planetaries, heaviest line-pressure springs - matter of fact, the gray line-pressure spring is the one included in the B&M and other performance shift kits.

B-O-P engine flange is different shape than Chevy, but a number of 700R4's had dual pattern, to fit all engines.

The 350cui engines would have the heaviest duty construction - the 4wd case is heavy duty.

2wd cases have large "C" cast, 4wd has "K"

Again, the D4 is hd torque convertor for Diesel.

'88-up has all the factory upgrades and improvements

'82 6.2 swb fleetside w\700R4, 3.00:1 diff, 7.00-15 tires will still regularly return 27mpg daily driving, city\hwy

Good luck with your search