Cevin Waffle

I just replaced the serpentine belt on my ISL 400 and bypassed the the compressor (until my new one comes in). On mine, it is one belt for drive everything. It is long enough to work around the fan. I did have to replace the bearing on the fan hub and I replaced the fan with a Source Engineering version, much quieter now. Once the fan hub was loose, it was much easier to work around. Did most of the job through the floor in the closet. If yours is similar, it can be done but is very awkward. 

I just had the same problem and bypassed the compressor until I replace it. I have a 2008 Diplomat with the ISL 400, rear radiator,  but sounds like the same belt path. I used a Gates #K080734HD, 73" and worked fine. Goes right under the compressor to the alternator. You should also look at the belt tensioner and fan hub bearing, changed both of these at the same time.

I'm dealing with the same problem now. On my '08 Diplomat it uses the SCS Fridgette 094-00187. I have currently bypassed the compressor until I have time to change it. I did find that when I went to change out the belt that the fan hub bearing was worn letting the fan move back and forth a little. Figured this was a good time to change to the Source Engineering version and changed the belt tensioner as well. The fan change was a challenge but was worth it, considerable quieter. On my ISL400, I used a Gates 73", 8 rid belt to bypass the compressor.