I'm thinking the 4t80 trans is a good alternative for the LS4 swap. The price to build a 4t65 to hold the LS4 would cost alot more than this pan starter combo .
LS4 powertrains came from the factory attached to a 4T65eHD transmission. That is how GM designed it .
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The 4t65-HD with an LS4 had 303 hp in factory fresh condition and it's known for failing under warranty. One of my 3800sc cars, a Riviera series1.5 charger(?) had a warranty replacement trans which was failing again by the drive chain slipping if you give it any throttle at all. The car had zero mods.
Joe, that is one of the prototype oil pans from the development of the LS4. So at one point GM considered the starter below the oil pan for the LS4, but opted to move it to the transmission prior to production.