Good read here. I pretty much take anything James B. or Chuck/Vince @ FLT say about a transmission as fact.
https://www.performancetrucks.net/fo....+transmission

 

The 4l60e has a overrun clutch that only applies in manual 1,2, and d3. The overrun clutch has two purposes it supplies engine braking and it reenforces the forward sprag. The forward sprag is known to fail during high horsepower high traction downshifts from od to 2nd. If you know you're going to drop or get into a roll race you should put it in d3 so the overrun clutch will help the sprag.--------------------------------------------------------------------------------

 

Broke two sprags before. Some shops replace with OEM, but others replace with BW parts (for "additional" strength). I went back with OEM (b/c of availability the day I needed it).

SpdFrk, If you're getting an FLT5 (like your sig says), you should be satisfied. I have a friend of mine (also a PT member) with one in a Z71. Tried on several occasions to break it with a bolt-on 6.0L & a mild shot of juice.

BTW, Matt... STILL WAITING FOR THE 4WD BURNOUT! Right, Vince?