Here is a link to a thread on the HAMB site.
LINK If it doesn't go to the right page the post is on page 4. This guy says that the hydraulic roller cam from a '87 Fiero 151 will fit a 181 Mercruiser block. If that is true it will fit a 153. I have never seen the cams side by side. I know all of these engines use the same timing gear set and the same cam bearings. I have a rebuilt 151 that is the later undesirable letter code. I forget what it is. N or R? It seems to have two distributer mount options. One in front like a 153 and one in the back like the 151 I pulled from a YJ Jeep. In the rebuilt engine I can feel teeth on the cam in both holes. Anyway this is worth checking out.
