Trans slippage?

When it shifts up or down shifts into 2nd gear the trans will slip when the the R's get over 4k at full throttle. I have 57K on my truck, at 13k the trans was rebuilt and the valve body replace while they over looked a cracked 1-2 accumulator. After two weeks in the dealer they changed the 1-2 accumulator. It ran great untill 55k miles and it started doing the same thing sliping in second gear. So I bought a 1-2 and a forward accumulator, corvette servo and a hard plate put them in. It shifts better but it jumps or skips rather than slip. please help thanks

time for a rebuild.

The accumulator only cushions the shift....if it's broken it will likely shift hard. You've put an inappropriate band-aid over a sore that didn't exist. Make sure you send copies of invoices from parts you've installed as well as the stuff the dealer did to whomever gets the joy of fixing it as they'll need all the paperwork (not just a convoluted story about what happened) so the problem is clear.

A Rebuild? Thats what I was afraid of. Any sugestions on a good 4l65 upgrade kit?