I have this model truck and would like to replace the engine. I got another FE engine but the crankshaft gears are different. The original one has a tapered insert and the new one has a keyway. The u-joint pulley mount holes are larger on the original one. The original gear has a pin that fits into the u-joint pulley and the new one has the keyway on the gear. How can I change over to the new and still use some of the old parts. Can "I grind down the new gear to fit the old pulley? Are there other models that are close? Please help. Thanks, Jim