i have the 4t60E with 227,000 miles so i need to start p;aning on a replacement so im ready when i need it. but can i swap to a 4t65E HD with out a tune or would i need one ?

thanks

You would need to add 5 wires from the trans to the pcm and swap it out with a year pcm that had the 4T65. If your car is supercharged the ideal pcm is a 1997. If not, you'd need to change the wiring harness as the pinouts at the pcm are different.