Well I imagine Holley was trying to sell to a larger group of customers and add the additional 4 lower holes to fit various other transmission.
As for the 45-545RFE transmission that I'm using both parts are a fit. My only worry as mentioned above is the oil pan rail pattern.
-- I was looking and notice that by using the Tran mount holes and a deductive reasoning the pan bolt spacing "looks" to be the same. If you look at the angle pictured below you can see the rear pan bolts look to be the same width apart from the opposite side by using the hole for the mounting to the transmission. What does look like it might be off is the spacing between the forward and aft pan bolts. its hard to tell to me because the stock parts looks to have more (meat) material in this area where the Holley parts seem more streamline (cleanup) in that area and I can't tell if its off or an play on the eyes due to the amount of martial between the two pictures...
Anyway I found a used one on flee-bay for 20 bucks so I'll bite the bullet and test it out...
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