Motorcycles, Snowmobiles, Go-Carts, ATV's and Golf Carts - kgro mower deck question

I picked up a basket case kmart brand mower with an 18 hp B and S engine and 42 inch deck. It is a 1994 model and had been sitting in a guys back yard for a few years not running. It had been dismantled pretty well and the deck was off of it. I got the mower back together and the deck on, but can not figure out how to get the belt tight enough and lined up so it will engage the blades! I have three pullys on the deck; one for each mandral and a third one forward of the other two and inline with the one on the motor. I do not see anywhere where there would have been a fourth pully, but the belt is at least 3 inches too long. The guy swears that this came off this mower and that it worked when he removed the deck. Can a drive belt stretch from sitting??? Any suggestions or should I go buy a shorter belt?

I would look under the steps on the side of the mower or the rear wheel hubs to see if the factory placed a sticker showing the belt position in case of replacement. I have a mower with a metal rod mounted on the right frontside of the engine pulley which takes up an additional 3 inches.:coffee:

I have a metal rod on the right side og my engine pully?? does your belt go infront or behind this?

I can't give the exact belt lay-out but a shorter belt is not the answer.
Threading the belt is a little akin to fitting a belt on a clothes dryer.
I used to be a groundsman and had a Toro with a seemingly convoluted belt lay-out but it all makes sense when you see it all together.
I suggest you contact a dealer I would think they' be only too happy to help out with the info you need.