Had my trans rebuilt with a monster kit. Any fluid recommendations thanks in advance

 

AutoZone sells Valvoline synthetic fluid for about 25 bucks a gallon. Any name brand quality fluid would be acceptable in my opinion. The Valvoline seems to be a good deal

 

For synthetic, genuine ACDelco Dexron VI. You can usually find good deals on Amazon for the gallon jugs - ~$20 ea. If you're happy with dino, I've always used Valvoline's dex/merc.
Pretty much anything other than the latest low viscosity (eg Mercon-LV) stuff works fine. Oh, and note CVT trans fluid is totally different too.

 

I agree with the above, I use Royal Purple because my 200 4R was built by a very good friend of mine that's one of the well known Buick GN builders. And that's all he uses