The 4T60 is nearly the same trans as the 4T65. The major differences were the change from a mechanical shift pressure mechanism (modulator) to an electronic soleniod (EPC which fails more than the vac ever did), a larger diff in the 4T65HD, a pump capable of higher rpms without cavitation, and a 4th clutch hub that was known to strip easier. Those were the 4T65 improvements in a nutshell.

Not sure where Cam gets the part that it's fragile, it's not.. it doesn't like high rpm though.