I know this is an old post, but here lately been going through them and finding ones that I think are interesting.
Anyway, these tractors were available with either a 12 speed manual or full powershift transmission, a choice of either a 855 Cummins or a Series 60 Detroit Diesel. These tractors are the same as a Massey Ferguson 5200. When McConnell built these, only the models 1000 and 900 were offered. McConnell was bought out by AGCO in 1995 I believe, so a pretty short production run. Look up Big Tractor Power on youtube if you have a computer, he's got some videos on a MF 5200 and a McConnell Marc 1000 I believe.
While looking at some of the pictures from Massey Days 2013, I thought the 303 Work Bull was interesting. I have heard MHF built industrial tractors but have never seen one. Looks to be based off of a 444 Massey. Also thought the 44 LP w/2 row mounted picker was an interesting machine as well.