1987 GMC R3500 dually with th400
 

I have 1987 GMC R3500 dually with th400 I was wondering what upgrade I can do with th400 for hauling towing

Re: 1987 GMC R3500 dually with th400
 

I used a B&M Traveler torque converter designed for towing and a 34 element sprag and a deeper pan with cooling tubes for mine along with a complete overhaul. I know there is more you can do but this is what my budget allowed. Look at mikestransmission.com and other simular sites to get more ideas. My 1987 Cab and Chassis already had the heavy duty transmission case. I ended up parking the truck after about 20,000 miles due to engine problems and not needing a heavy hauler anymore.

Re: 1987 GMC R3500 dually with th400
 

new fluid, and a good tranny cooler. th400 are pretty tough.

Re: 1987 GMC R3500 dually with th400
 

x2 tranny cooler. These transmissions are pretty tough as is. Just keep it from getting too hot and it'll be happy.

Re: 1987 GMC R3500 dually with th400
 

Beyond a fluid change + fresh filter, a trans cooler & shift kit are good investments.

Re: 1987 GMC R3500 dually with th400
 

If you are going to keep the truck and want better mileage update it to a 4L80E transmission with overdrive and a lock up torque converter. If you spend any money on the TH400 other than a shift kit and filter change you would be much better off spending the money on the 4L80E swap. Transmission cooler and cooling pan are good ideas for any Heavy duty transmission.