[jwhotrod]

also, do yourself a big favor and use genuine GM starter bolts with the knurled shank and washer heads. the starter holes in the block are 3/8-16 with a .375 c'bore above it for that knurl. that knurl/c'bore combo is there to act as a dowel pin to properly locate and hold the starter in position. that is especially true if you use a mini starter, which a lot of us use with headers, etc. that starter has a 10mm hole thru it above a 3/8-16 thread on the bottom. the correct bolts are cheap at your GM dealer, last time i bought them it was $8 for 5 of them. i was breaking bolts on the 409 in my streetrod until i figured this out. good luck.