A real common traction belt is 37x61 and is closer to 95". I looked through the OEP book and didn't see a traction belt close to that in length. Cleaning the frame rails is a good idea because that rear idler complex can get bound up. Frequetly you need to replace the composite idlers too. So in the olden days, Murray Microfisch was done by year. Maybe sifting through info on partsandservice.com will get you where you need to go.

i assumed the belt length i needed was 94-95" but i could not find that in the catalog they had at store. but than we found the "murray" belt in that size on the rack so we went with it. i figured a 1" shorter belt would help. the rider does move now. better it seems. forward seemed ok but rev was weak. so i adjusted the rod 1 turn and rev is better. i still think the belt is kinda loose with the clutch released. we got it with no deck but the snowblower assy was attached. which is much more complicated than a mower deck.

Drive belt = Murray part # 037X87MA

Size = 1/2" x 97-1/16"

Others that will fit.

Oregon 75-209

Podoy 710341

Auto parts store and other such places. Look/ask for a 4L970 belt.

Tip: Advance, NAPA etc ask for a belt that the part number ends in W if possible. For example 4L970W. They last a lot longer than regular belts.

Jack,s Small Engines has your oem belt sizing (95" x 1/2" ) as Part # 265306 for $13.34 otherwise Napa is a good local fix as suggested !

97"? thats getting longer, not shorter. how snug should belt feel with clutch released? we measured belt folded over with a tape and it was 47.5" approx so we doubled it. and found the 95" belt. a 97" is too long

As I said Jack,s has Oem belts for the Murray Ultra check their site . Otherwise Napa normally has aftermarket belts as Mule advised . Depending on the usage your belt will have some stretch from wear . I have always cross referenced to Gates but that's just my preference .

I miss Fleet Farm.... Anyways have you had a good look at the drive pulley? Years back those stack pulleys would split if my memory serves correct. Belt should feel snug. Hydros had the double idler configuration and were pretty reliable as far as maintaining tension, though you have to watch over the pulleys for wear. They seize and melt away. Brake isn't tight?