(quoted from post at 20:10:50 08/09/16) I've done one IH and that was a long time ago. If I remember correctly you need to take the drive plate loose from the front of the crank to get the belt in.
One other option is to get one of the twist together belts and make your own. I just put one on a Harlo lift where there was no way to change the belt without draining the hydraulic system, removing the pump, etc, etc. The twist together belt carries the same HP rating as it's continuous counterpart, and will go on without having to remove anything.
I ran into a similar issue with another tractor a few weeks after the Harlo. One the drive shaft to the pump would not screw out, and two, we had never been able to get a belt the right length for the modified charging system (alt -vs- gen) due the adjustment amount being severely reduced by a part of the frame for an attachment. So I got another twist lock for that machine. Not only did I not have to take the drive shaft to the pump loose, I was actually able to get the belt tight, like it should be, because I was able to run everything in, and put the belt together in place to the optimal length.
Below is a link to Fenner's site showing the belting I am talking about.
Fenner Drives
Thank you for the info! I'd briefly heard about these belts but couldn't look them up. I may be beyond that application as I have the belt in the mail & have headed towards changing it out including losing all of the hydraulic fluid. How did you figure out which belt fit your application?