I bought an '87 Suburban 5 years ago. A week later the 700r4 transmission would not shift from second to third gear so I changed the filter and fluid. The pan had some silver junk on the bottom and the fluid had that silver look to it. For the next four years the transmission worked fine. Just recently the problem started again and I changed the fluid/filter 3 times but just got worse.
I took my truck to a Transmission shop and laid out 1300$! to get the trans rebuilt. Two weeks later the trans is doing the same thing. Under slow acceleration the trans will stick in the 2-3 and/or the 3-4 shift. It shifts better when accelerating hard, at times it stays stuck in second gear and is undriveable. The weird thing is it doesn't do it all the time; I'll park it for a bit and take it for a spin it will shift fine. So I brought it back to the trans shop and of course the transmission shifts normal while three of the mechanics drive it. If anyone has any ideas on what the problem is I'd surely appreciate it.

 

The problem is you will have to leave it with them until it does act up! I am in the tranny business and it is tough when a tranny won't do what the customer says but if it doesn't what can you do?

 

Sounds like you are missing some material off the 3-4 clutch pack. Mine had two frictions, ummm.. lets say friction-less but the 2-3 shift was still ok at WOT but a little sloppy at part throttle.

This wasn't even the cause of my rebuild, it was lag time between 1-2 because of a wore out/burned band.

That would explain the metal shavings. I had alot myself, all from the 3-4 pack and partly from the rivets holding the band material on the steel backer.