I believe the 242 and the 245 share a front case. It's the "middle" section that holds the overdrive stuff. The 242 lacked this because it was the four speed for the 1977-79 320 cars.
You've got the right one. Now start the conversion!
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ClayW
1976 Fjord 2002 Sunroof
Project Blog
"Finish the thing, do it right the first time and drive the son of a bitch!"
-Gray Baskerville on hot rod advice