1984 GMC Suburban from North America - Comments

There were only 2 things that have gone completely wrong with this truck since I've had it.

At about 340,000 kilometers, the second transmission had failed and I had a different one rebuilt. It was a manufactory defect from another garage that cost me $1,300. Since then there have been no problems.

The second problem was the glow plug timer which has fried all of my glow plugs. I easily remedied this with a new solenoid and toggle switch for manual operation. Works fine now.

This truck has a lot of power for a non turbo diesel but handles like an old living room couch. Which is fine because I don't often run from the police.

The bench seats hurt the back on the longer trips and despite it's immaculate condition inside and out, sadly little spots of rust are forming and the bottoms of the doors are brittle and flaking away.

Does anyone know what transmission this truck is supposed to have because the mechanic tell me its supposed to have a 400 but mine has a 700r4 and I don't know exactly. please help.

The answer to the question above is some GM and Chevy trucks came with a Turbo Hydromatic 400 Heavy duty 3 speed auto and some came with a Turbo Hydromatic 700R4 Medium Duty 4 speed auto depending on what combination engine, 2 or 4 wheel drive, half ton or three quarter ton you ordered. Not all combinations were made available due to GM/Chevy wanting to simplify their manufacturing combinations. With the Gas V8's the TH 400 3 speed auto will give you better performance and durability at the expense of ecomomy. The TH 700R4 is more efficient because of its lock up torque converter and overdrive, but it is medium duty, as opposed to heavy duty like the TH 400 3 speed auto. The Diesel V8 with its modest power and low redline is much better suited to the TH 700R4 with its overdrive gear. If you have a Diesel V8 with the TH 400 3 speed auto your truck will not be able to go much past 60 MPH without damaging your Diesel-V8 engine due to overrevving. To make your TH 700R4 last longer, change the automatic transmission fluid often and install a transmission oil cooler if you are driving it hard or towing heavy loads. For every 10 degrees cooler you keep the TH 700R4 tranmission you can expect upto 25,000 miles more of life from it. Also select the D rather than the OD selector on the gearshift for city driving, hilly terain or when towing. This will also make the TH 700R4 4 speed auto last longer. Hope this was helpful.

I totally agree with the above. I have a 700 trans that was beat on for 20 years and just went. the lock up torque adds fuel miles, but drops heavy duty qualities. my brother has the diesel with a 400...he's changing it to a 700.