IIRC, the front section of the fluid coupling has the starter ring gear made onto it, so it should be sufficient to crank the engine without a problem. The short "bellhousing" ring that adapts the transmission to the engine also has the starter mounting bolt holes, right? It's been a very long time since I've worked on a dual range transmission in a GMC or a Chevy truck!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!