1989 700R4 going into a 1984 K20 Chevy Suburban

[62ChevyC60Wrecker]

My 84 K20 Suburban's transmission crapped the bed back in the last week of October; I just got a used 700R4 put into the truck. I was watching "Youtube University" and this channel I was watching the host put up on teh screen the 700R4 had several "generations" on the 27 spline output shaft & the 30 spline shaft was started by GM sometime in the late 80's. I will be counting the splines on both the transmission today (1-1-2024) between the used 700R4 and the NP208 transfer case that backs it. Any suggestions on what to look for parts wise that would be the cheapest way to go as I am doing this on a budget. I am considering getting another driveshaft made; (if need be) and leave the T case out for the winter; although the truck won't be 4x4 this winter. Any suggestions? This is my first transmission swap and I don't have a 2 post lift in my driveway; I am laying on the concrete doing this. I also have to swap out the shaft for the shift linkage that's tied in with the rooster comb as well. I will be pulling the pan off the dead 700R4 to figure out how to disect the one in the truck as the shaft broke at the side of the case. I have the removal and install tools for the seal. Those just came this week from Amazon.

[kwmech]

With my knowledge and personal experience with 700s I'd say go with something beefier in that Suburban...like a 4l80e. I've had 2 'burbs with 700s and never had any luck with them. If you are doing any towing or somewhat serious wheeling they just don't last. My opinion is that the 700s should never have been used in a truck. Another thing, a cheap and lasting 700 does not seem to go hand in hand. I had a 1990 suburban with the 700 that went south at 120k miles--(factory trans) I had it built at a local shop with a bunch of upgrades. Trans went south 45k later. I put in a ''factory rebuild'' which is nothing more than a rebuilt put together by some other transmission shop with a GM contract. Had that in for about 50K miles when it started acting up. I sold the truck ---big mistake I loved the truck other than the issues. Now I have a 91. It had a 700. Came home one night after grocery shopping and put the truck into park and it kept rolling. Pulled the pan the next morning and fount a piece of the rear planetary wedged in between the parking pall and the notch hole. Wasn't going to do another 700 EVER!, I converted to a 4l80e. I have other experiences also with the 700, but I'm tired of typing. If somebody comes into the shop wanting me to work on one, I send them to the trans shop and let them have the headache. A little distain??--you bet

[62ChevyC60Wrecker]

The one I pulled out had over 275k on the clock; the truck had about 260k on it when I got it. The fluke that was the demise of the 700 out of my truck was the filter decided to leave it's home & drop to the bottom of the pan; the plastic washer was still up inside the bore & as I was looking at this I was thinking "WTF happened here"? Lucky for me it happened when I was almost home from work; and I don't have to drive the highway. My dad had a 91 burb with the 700 in it & he never had any issues with it. His was a 2wd model though & he never towed anything susbstantial with the exception of a trailer that held a yard of concrete when we added an apron to the driveway. I have also seen various videos on youtube university and the trans rebuilders were covering various pros & cons over the 700R4, 4L60 and 4L80 transmissions.