73-75 164 can use the 240 parts. We've upgraded a few over the years, added power windows, locks, late model GL armrests, seats, even changed out the dash top for the later type with the radio up top. It all basically fits and screws together without any major issues.
My friend has 1990 240 leather in his '75 as well as some upgrades to the interior panels and such. Given how cheap a rusty '84 GL is these days, the parts can be had pretty economically....
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Rob Bareiss, New London CT ::: 86 244DL, 87 244DL, 88 744GLE, 91 244: 808K total

The later the year of the 164 the more likely this is to be true.
Not too much in the case of my 164, 1969. The big change was between
1972 and 1973.
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George Downs, The "original" Walrus3, Bartlesville, Oklahoma