Right now I'm leaning towards 3925505 as it has the Bellhousing mounted starter and the 5-1/8" center hole. I'm just a little nervous about how far outboard the starter sits as it may interfere with my front driveshaft. Tomorrow at lunch I'll try and get ahold of someone at Novak. There may be a good reason why they recommend turning down the SM465 bearing retainer a tad and opening up the bellhousing center to allow it in. It could be that the ideal Bellhousing for this is playing cards somewhere with Santa Claus and the Easter Bunny.
