For my Greymarket tractor I bought a Douglass 60" Finish mower as is,which is a 5', at least I got the printed out(copy) manual for mine from the dealer which has all the parts numbered,as with the belts both mine were not with this finish mower as were quite a few other parts, I didn't need anything more than a 4' but the price was okay for this incomplete unit, the dealer did include a new PTO sliding shaft minus the complete saftey chained PTO guard, even with ordering the missing parts,which included 4 tires/rims , 4 wheel spindles , 2 axle beams , 3 new blades, 2 new pulley belts, small hardware like new bolts ,spacers etc. I'm still waiting for the 2 belt covers(guards) and the one side deflection blade guard , which are still on back order since over a month ago,I guess I'm lucky to get the parts I most needed to be able to use this finish mower as is, so you should have no problem with the belt issue or anything else other than guards that really don't often need replacing, I know it cost me as much if not more $$ to almost complete this one of mine , but I think of it this way my own labour like sandblasting and repainting it, when I have all the needed (back orderd) parts I'll have a nice reconditioned finish mower, as for the missing parts I've mentioned, even if I don't ever get them, I have a small metal bender (brake) that I can use to fabricate them myself (no big deal), I notice your finish mower manual shows only two rear (tires) wheels, where mine has 4, so I gather the 3 pt. hitch keeps the front end level along with the 2 only rear wheels, I'm wondering which is the best design maybe someone can chime in here with an answer as this type machinery is new to me, anyhow just read your manual it should show the belt size you need, the manual on mine shows a 4' and the 60" and 72" using the same size belt,.........take care.... AMPA