I have an 850DP model 0-4781-7. I would like to know what the -7 represents as my Holley book has info on everything up to -5. Also I would like to know if the metering blocks are the correct ones they have 8543 stamped on the front unit and 9108 stamped on the rear.

You might want to try www.holley.com and look up your list number. You should be able to find all the info you want there.

I tried that and couldn't find my specific request......

4781-7 is listed on the sight. It does not say what the -7 means. Your primary meter block should be 34R11799ADQ, and your secondary block should be 34R9109-3AMDQ. I would give Holley a call and ask them it's cheap 270 781-9741. I would interested in knowing what the -7 means as well.