I read where some of the street rod guys were using two turbo 400's just the way want to use to 3 speeds. The second unit was for underdrive. They could gear them down with 2.56 or 2.41's then shifting both transmissions they could have a real low first gear.
A simple slip joint between the two should work! You also shouldn't need a clutch on the second unit, Just shift it into overdrive before getting going. You could use 3 gear as 1 to 1 and 2nd gear for overdrive. Tractor guys do it all the time for crawling speed when fabricating drivetrains! Joe
