Re: Two prop questions!
Yes, the thru-hub exhaust prop will fit the 1988. It will give exactly the same performance as the same diameter and pitch closed hub prop.
P510 refers to the prop itself and was an old Chrysler designation that I believe Merc and Michigan carried. I know I have a p510 in my garage but not being dressed (TMI?) I am not about to go outside and look.
It will either be a stainless or aluminum (i forget the terminology--for example 510 would be stainless and 210 would be aluminum in the same design and size) and usually will have another number associated with it -- 510-17 meaning a 13 3/8 diameter by 17 pitch.
It will most likely be 17 or 19 pitch.
If you are truly interested I will look tomorrow and reply again