I am trying to find oil pump drives for a Gen VI motor. Having a problem finding them. Are the old Mark 4 the same as the new Gen 6 ? I know the pumps are the same but how about the drives ? Milodon says they don't make one, ARP just lists 1 for the big block like they are all the same.

Brian,
I did not know there was a difference. I have always used the Melling drives with the solid steel sleeve, I think the number is IS77. That is the only number that Melling lists. I have used them on Mk4, Gen5 & 6 engines.

I can not speak from experience about Gen V but I can say with certainty, that Mark IV and Gen VI are the same. It would be very likely that Gen V are as well.

That sounds about right. I got confused when Milodon said they never even considered making one. Maybe thay don't make one because they are the same as the old ones ? I am going to order tomorrow so if anyone else has any imput now is the time, thanks. Very confusing being sure of parts interchange between the different generations. I notice ARP lists two different length intake bolts for the big block. Anyone know what's up with that ?

The drive rods are the same for all big blocks. The intake bolts are probably for low deck and tall deck. The flange of the intake where it meets the head is much thicker on a tall deck, hence the need for a longer bolt.
Eddie

The intake bolts come in two different lengths. 1.25 and 1.5. No mention is made of tall deck and short deck. Looks like the 1.5 is used on what they call a 502. The 1.25 is for a 454. Seems like they are calling the Gen 6 a 502. I need to verify, but I believe I need the long "502" bolt.

Melling can supply two lengths of rod to cover tall deck and standard deck. The Melling HV / HP Pump (10778 / 10778c) comes with a hardened shaft rod whereas my M77 came with an alloy shaft with a platic sleeve to cover the join onto the pump.
I only know this because I pulled an M77 off mine with the alloy shaft and the 10778c I bought to replace it has the hardened shaft with a built in sleeve join. Both shafts are the same length, I think you have to specifically order the longer shaft for the tall decks.

Standard tall decks (10.2) use the same oil pump drive.
The only time I could see the need for a longer shaft is if you had a raised cam situation like found in the "really, really" tall decks

Dave