I have this riding mower and need to know the # for the blade engage belt. The one on there is too big..

Any small engine shop should be able to (by the numbers off the frame) get the belt...
Is the belt original?

No I don't think so. A friend gave the mower to me.

Al u have to do I go to the mower shop and have them runn the sereal number on the mower and have the right belt for it if they can find the belts sise

All u have to do is go to the mower shop and have them run the serial number of the mower and they will be able to finde the belt for u

there should be a sticker or plate on the bottom side of the seat, or on the rear of the unit above the hitch. Get the model # and purchase an oem belt. I would recommend staying away from automotive belts as they tend to not last very long. Also, a tip about murray belts is that some people will think that if it is, lets say a: 37 x 88 that that must mean the belt would be 88 inches long, this is so not true. That is just a part number that murray used. Murray is now owned by briggs and stratton, so do not only search for a murray dealer, search for a briggs and stratton dealer and they will be able to find the correct belt.