Great question. The T15 is a strong transmission, for sure, but that info is correct. The J-Truck T15's had an unusually long input shaft to space the transmission back closer to the driver. Because requests to retain these T15's in these Jeeps has been low, we've not developed a casting for it.
However, we have used the existing T15 casting from Jeep and married it to our Chevy bellhousing adapter. It takes some machining - about an hour and a half, but can be done. See the enclosed photo - and let me know if your factory casting looks like the one shown on the transmission.
Because this has some expense, some installers jump to the SM465, and that's not a bad choice but you may not need four speeds and a compound low gear.
Let me know what you think and how we can further help!
