I have a 408 Stroker in my 70 Duster. Just had it put in. After the installation, the distributor blew out when I tried to start it after about 20 miles and maybe 10 starts. I went to start it an no spark on the 11th start. So I figured well, it's probably the distributor, it was brand new, a Pro Form brand dist. I replaced it with a semi-stock one that lasted about 3 starts and ran maybe 5 min. On the fourth start, no spark. So that tells me it's not the distributor, lol. I plan on changing out the ballast resistor, and the distributor again, but this is getting pricey. I don't know for sure the ballast is what blew them out, is there any way to tell what it is? Diagnostic?