early Jackpiner cases

[wildman]

I have two sets of jackpiner engine cases, one black set fron 72 and the other silver from a 74. Both have the same part # on the castings but the later set has "magnesium" next to the part#. My question is: are the early black cases magnesium or aluminum? I couldn't find anything in Search. They look identical in every way otherwise, except the later cases are rotten. Thanks for the help, Dan Pagel

1975 250 Cross Country, 1974 175 Jackpiner, 1975 125

[Larry Perkins]

They are magnesium.

Larry P