FLT lvl 3 vs lvl 4
 

What is the major differences?

Only things I see are overrun pistons and HD 2-3 shift valve mod and maybe a different sprag?

Trans is slipping. All stock DD for now. Maybe headers and tune in the future but stock for now. Truck in sig.

Money is tight but wonder if it is really worth it to go up to the level 4 for my purposes?

Just kinda price shopping right now. GM crate with 3yr/100,000mi warranty isn't looking too bad either.