Hi, I have just buy an old Murray 16 hp twin Briggs & Stratton tractor from about 1977 (Model Number 9-4166 Date of manufacture 9120). It have a 4 speed manual trans and another lever on the right of the shifter, but I don't what it do. What is the model number of the Brigg 16 hp twin engine, because mine take oïl and don't run perfectly. The previous guy made an home made front loader (very well done) and add a big cabin with hydrolic lift and 2 hydrolic cylinder in the back for a kind of 3 point Hitch. He put a heavier front axle with bigger tire and part of car front linkage to the wheels. He install a big pump Under the tractor but the strap slip (no spring to tighten the belt) and the transmission slip too, but I don't know why, maybe for the same reason. Need some help to correct this or find another Murray tractor in good shape near Montreal, Quebec, Canada. Thanks for reply.