I just replace a transmission in my 98 pontiac grand prix and was wondering how many quarts of transmission fluid does i need to put in it i have already put 7 quarts tia

Replaced your transmission with what, a rebuilt, remanufactured, or junk yard dog? In the case of a remanufactured 4t65-E it is likely bone dry and if I recall the capacity including torque converter is 13.4 quarts. In the case of a rebuilt or junk yard transmission it all depends on how much fluid is left in the torque converter. If it'* one of the last 2 you'll likely now need to add a quart at a time and check the trans dipstick between quarts. I hope you're using Dex VI.

Agreed, Dexron VI is the best move these days. WalMart tends to be the cheapest source for it, and the preferred source on account of that.

7.4 quarts for pan-drop+filter swap, 10.0 quarts for overhaul then check and fill as needed after it is installed and running again. If there is some already in it then I'd start 7 and work up to full hot.

Yeah, always prefer Dexron VI. It gives friction durability which gives a very nice shifting performance.