can i switch from a 4L60E to a 4L65E? - Here it is, 1999 Silverado LS Z71 with 160K on it. 5.3L Vortec, and 4L60E transmission. On occasion transmission will ...

Here it is, 1999 Silverado LS Z71 with 160K on it. 5.3L Vortec, and 4L60E transmission. On occasion transmission will shift very hard in to 2nd and hard into 3rd. 3rd to overdrive is smooth. it does this when its been driven for awhile, and while being driven like a "grandpa". I figure its time for a new one. What i wonder is, can i replace the 4L60E with a 4L65E without any issues? Would i gain any durability benefits from the upgrade? would i have any problems? Im not too up to snuff on the newer transmissions, but i believe the 65 is the HD version of the 60, built to handle the power of the 6.0 vortec, also in 2002 the changed all light duty transmissions to the 65 correct? mainly i wanna know if i can upgrade with no bolt up problems or computer issues? thanks!

Yes it will all bolt in . 4l60e have two different input shafts and pump. If your transmission has small 1/2 o'ring the computer strategy is different for lock up. If your trans has 1 inch o'ring on input you will have no problems at all.
The difference is the rear planets has 5 pinions in the 65e. If i was you i would have your trans rebuilt and have them put the 5 pinion planets in it. They fit with no mods needed. Also have them install transgo shift kit, The Beast sun shell, unbreakable pump rings, new accumulator pistons, and larger cooler if you want it to last longer.

once again, price range? the full rebuild vs. new tranny?

Just a reminder you pay for what you get. You cant buy a new transmission. You can buy a reman from huge factory that uses the bare minimum in parts that's what the dealer will sell you. Or you can spend the money and get it done right. Every city prices are different around here we would do the complete job for about $2500 that's every thing. I have worked for shop that charge $3500 for the same job.