Solid once piece dowels for sale brand new and are for people who have done the rear iron external oil mod or have an external oil filter that reroutes to the front iron.
I will also sell single dowels for 50$ if you do not wish to do the bypass mod but wish to have the added strength.
(Not to be confused with "dowel pinning" two solid one piece dowels simply replace the four that are used to align the housings and irons. This helps cut down on engine vibrations and twisting with high horsepower builds )
increases block rigidity
During assembly you will have to use the stock dowels to line up the irons and housings then once you put the intermediate iron on you can remove the stock dowels and insert your new one piece dowels. Here is a picture example
