Originally Posted by knightmare1015
That's not too bad on that engine, but I would have it rebuilt. The good thing is that you got a 351 for free along with the tranny. If I was you, I'd do some research a bit while the engine is getting rebuilt so you will know what's involved.
X3 on the rebuild, mine required both engine and tranny rebuilt, still running great. As for the 351, just a bit more goes into dropping in the larger engine and requires alot more research from those that have already done this type of swap. Moves like a raped ape afterwards. Would highly recommend an 8.8 31 spline rear from the explorer or 9" to handle the extra torque from the tendency to show off every now and then.