I have written about this before but I can't take the time to find it and repost...
And I am not trying to dis or denigrate anyone else on here that has a lot more mechanical smarts and experience than I do...
BUT...
From a transmission man standpoint, one who has seen bunches of pump bushings worn out or worse, spun out and thereby chewing up the pump housing so as to make it un-useable...
AND seeing what happens to the rest of the transmission over time while it slowly contaminates itself until you have ATF pouring out of the front seal...all from a 'slight' misalignment from the back of the engine to the front pump of the transmission...
I am not going to recommend trying to adapt any 460 case to the diesel. Period.
Yeah, yeah, there are those that say they have done it and driven a million miles on it...
For me, no.
Not unless I happen to find myself in a post-apocalyptic world and I gotta 'just' throw something together to run over and smash a bunch of zombies.
For the world we find ourselves in right now with the money and power-hungry revenooers out there just waiting to write another book of tickets and thieves waiting to bust your windows and steal your stereo and tools I am not going to chance a breakdown and sideline to a dumb thing like that.
The clearances for the pump bushing, torque convertor, and the engine-to-transmission case alignment are measured in THOUSANDS of an inch, not 'tenths'.
I have never been able to drill a straight hole in my LIFE...without some kind of jig.
If you can pull that off, more power to you...but...'they' stopped making C-6 pumps decades ago.
Going the 'other' way...that is...drilling a standard shift bell housing to bolt up to a diesel, sure, go ahead...it is only a bit more wear on the syncros and bearings and grinding up reverse gear a little more over the course of the units' lifetime before rebuild...you probably could get away with that...
BUT...reverse gear and getting to it in a ZF is expensive and a chore...but hell...it is your money and time. Have you tried to get any reverse parts for a T-19 lately..?
So...John...please...if you want a C-6, just find an original diesel case and build it up. You can convert any C-6 unit to 4x4. You need an output shaft and a good transmission builder to help you.
Don't forget to fix the problem with the number '9' thrust washer unless the thing has a needle bearing there. during the 1987-88 model year 'they' went to finally fix that concern.
And...if you get tired of messing with it...I will take the truck off your hands...that darn truck has always look extremely handsome to me.
'nuff said.