you were no help
42" deck = 71" belt48" deck = 73.8" belt44" SNOWBLOWER uses V-Belt 131"
You will need to order a manual on the mower from the manufacturer (I assume Simplicity).
I have Murray 42" cut riding mower that the belt came off. How do I put the belt back on?
A Craftsman 42 deck belt could be smoking because it is rubbing against something. There could also be an oil leak. If you can not find the cause, you should take it to be serviced.
Most LT12H mowers take a #213676 OEM belt or #6885 Gates belt for the blade application
just get new belts they stretch or buy a can of belt grip
The 42 inch deck belt is 104 X 1/2 inches.
the drive belt is 76 length 1.5 width
Impossible to answer without brand and model info.
One might learn how to install a 42 inch deck belt on a John Deere lawnmower by looking at their user manual. A better route to this may be to take it to a lawn mower shop for repair.
The belt length for a Craftsman tractor LT 4000 42 is 96 inches by three-quarter inch. This is assuming the same 42 inch mower deck is still in use.