Hi, can anyone tell me where to find the manual for a Magnum GP 10 engine. (Who is the manufacturer?)

Global hobby distributors is the distributor for magnum engines. I have a magnum .25 gp that I need a manual for. So far no luck. I wrote an e-mail to global and they don't have any information or parts for this model. From what I can gather the gp was a budget line of engines that was produced in the 1980's. They also had a pro version of some of the engines. The newer magnum engines are the XL line. I don't know if these parts will interchange with the GP line or not. You may want to post this in the engine forum perhaps someone there has one they can sell you or make a copy of. If I need parts I may just pick up a used one there are still alot of them out there. If you need a manual for basic information one of their newer models may be adequate for you. Some of the manuals are available in .pdf format that you can download from their website http://www.globalhobby.com/review/reviews.asp
Hope this helps.