Bill,
I would keep the T56 above the T5. it literally is 10 times the transmission of the T5.
The T4 and T5 are related, however the T3550 is related to the TKO 500 and TKO 600. The T45 and T56 share some parts. There is no other location of shifter on a T45 or T56. These are OEM fitment transmissions only. The T3550, TKO500 and TKO600 have 3 shifter locations (designed as aftermarket transmission), come stock with the shifter in the rear housing, however for about $300 you can buy a shifter for one of the other two locations.
No, you can not move the shifter for or aft on the T56 unless you have room between the transmission and floor. Then you can put a forward gimbal with a rearward connection to the stock shifter. It takes a bit of fabrication, however then you could do it. Problem is you need about 5" between the top of the transmission case and floor to pull it off.
If you want a T5 hybrid, I would put one together for you and swap for your T56 if you want.
No, the only T56 parts available with a mechanical speedometer is the T56 Retro. you will not find these used unless you are really lucky
http://www.sallee-chevrolet.com/BorgWarner/bwt56.cfm You could call TTC and see if they would make you parts.
Yes, you can swap the rear housing on the T5 for the mechanical speedo unit with the smaller hole needed to hold the outer gear and speedo connection, or if you have access to a machine shop, you could make a sleeve. The tone wheel clips to the output shaft just like the speedometer drive.
Another option for you Bill would be to find a transmission out of either an S-10 4.3 with the Getrag which will have the shifter forward and have the correct bell housing, etc. for the SBC (but is limited to about 250hp) or a ZF transmission from a full size K1500 which also has the shifter forward.
These are transmissions with truck duty in mind and will have a steeper first gear. The T56 is an automotive transmission with a shallower first gear and tight gear spacing.
The question is, do you want a truck for the sake of hauling stuff, or do you want a hot custom truck for hauling a$$?
The T56 would be best for the latter - in this case, put in bucket seats and keep going.
The Getrag or ZF would be better for the former - in this case, keep the bucket seats and keep going.
