Your 1986 Ford F150 starter bolts keep backing out and the starter keeps coming loose what can you do to fix this problem?

Use new bolts and locking washers, and apply loc tite to the threads before reinstalling. However if you have damaged the aluminum of the bell housing drilling and tapping the holes to a larger size may be necessary, or if there is room to drill all the way through you can use a long bolt with a nylock nut.