I have a 1974 fj40 with a stock engine & factory carburetor. I have an aftermarket header system also. The vacuum advance has failed on my distributor causing my cruiser to run like doodoo . I have tried to find a replacement vacuum advance, however they are not readily available from local sources or spector. I would like to know the best (and cheapest) way to repair this problem. Perhaps switching to an electronic type distributor?