I've had a couple of those. One truck, but a couple 700r4's. In stock form, the first few years they made them, they had a very poor reputation. I had one of these and it lasted until about 70,000 miles is all. Then, I had it rebuilt with a kit from Fairbanks Racing Automatics. The shop that did it said this transmission would handle pretty much any small block I wanted to put behind it. Another trait of the transmission is to generate a lot of heat, so get a big tranny cooler, and a temp gauge isn't a bad idea either. I really like the transmission now, shifts firm, doesn't hunt for gears, and the overdrive saves on gas. Good luck.
Like Mtck said the factory stockers are problem prone.I had one built last year for my pickup and the rebuilders are now puting 40 updates into these trannys.Also make sure that the tv cable is adjusted correctly or the transmission will self destruct.
if your putting one in,look for an 87 or later unit,the earlier ones had more problems,the 1989-93 were the best ones made in my opinion,they are fairly tough.The weakest area is the 3-4 clutck pak,heavy towing in OD without cooler will kill it.Tow in Drive,and make sure the lockup converotr works-this is essential,and put at least a 19KGVWR tranny cooler on it,and it will likey outlast your truck if you maintain it.The TV cable"kickdown" has to be perfect or you could fry the tranny in 5 minutes,seriously,it is the only way the tranny knows how much pressure to put to the clutch paks,if its set to low,the line press will be low,and you can then slip the clutches burning them out easily.I would swap one in defenetely,your RPM's wil drop 30% in OD.
go to the thread "would it be hard to switch a 700r4 to a 400.....i posted a reply there, but here is some more, i have switched from a 700r4..depends on what you will use it for ...
when I was just driving the truck with a 6.2 diesel which is what most 700r4's had it was fine. usually..but when I put a 350 behind it & pulled a trailer & pushed snow it didnt last long, rebuilt 700r4 in april 98, rebuilt transfer case july 98...6.2 diesel goes out & stuck a 350 in sept 99, feb 99 700r4 goes out & dropped in a 400 turbo...& np205 transfer case..havnt had a problem since..if you r just going to drive it might be ok but it isnt made for pulling..my opinion
I am in the process of replacing mine. It is a 700. The tranny shops tell me its not good to pull in overdrive because that will burn it up and you must pull in regular drive. Im having a tranny cooler put on mine and they say that it should last a long time if i pull in regular drive. I am also thinking of putting a drain walve in the tranny pan so it will get drained every two weeks or so. Ir pulls weight and drives all over all summer long so a few bucks on tranny fluid cant hurt. SOem guys tell me not change it too often if its going bad but it should be ok when its rebuilt. I hope.
Zipp660,just so you know,my 89 GMC 2500 LD has a 700R4,it has 145K on it,it has never been touched,except for fliud changes every 30K miles.I bought it from the original owner last yr,he pulled a 28 FT travel trailer with it,I pulled an 18 ft trailer during the summer,with up to 7500 lbs weight,It carrys a V-box,and plows all winter,and it is out basically with the first flake of a storm and doesnt come in til everyhting is done and salt/sanded.Oh yeah theplow has pro-wings,making the tranny work even harder.I agree it is not as strong as the TH400,but with basic maintance and a medium sized auxilary cooler it will hold amazingly well.To say it isnt up to plowing/towing isnt accurate,if abused even a Th400 will fail.My gross weight when plowing is 7500-9000,so it isnt light either.