The last time i checked, I think the option price for the Powerstroke and Cummins was over 5K over a gas engine. I might be wrong, but i think this is correct. As far as the Allison Tranny goes, it's not cheap but it would be worth it if it holds up and gives good service. Replacing an HD automatic will probably run you 3k or more.
I was at one of the local chevy dealers here in the area and they had 2 2001 HD 3/4 tons. Both were extended cab, one was long bed..the other short bed. They were pretty impressive looking, both cosmetically and mechanically. The frame is considerably larger than the previous generation truck's was. If any of you guys see one..look underneath the truck. Also, the salesman said the Diesel and the big block 8100 won't be on the lots till around Christmas or after the first of the year (at least here anyway). All the ones here in this area have the 6000 V8 with the 4L80-E automatic. The 6speed manual is standard with the diesel and the big block, and the Allison 5spd Auto is optional. They don't put the 4L80-E behind anything larger than the 6000 now.