4 speed Toploader maincases came in two bolt patterns:

The case on the right is a 64 narrow bolt pattern 4 hole case.The case on the left is a 65-73 wide bolt pattern 8 hole case. The inner bolt pattern on the 8 hole case is the same pattern as the early narrow case.


RF C4AR-7003-A:
1964 casting used in 64. Narrow 4 hole case.


RF C5AR-7006-D:
1965 casting used from 65-67. Wide 8 hole case.


RF C8AR-7006-D:
1968 casting used from 68-71. Wide 8 hole case.


1972 casting used in late 71. Wide 8 hole case.


1972 casting used in 72 - 73. Wide 8 hole case.


XAA 12512 / ALCOA 2:
This is a factory aluminum case used in 69-70 in factory road race cars to help lose a little weight. A very small number of these cases were made, maybe 10. This case had the HEH HG White Stripe gear ratios in it.


On production hi-performance cars, a partial VIN was stamped on the maincase of the transmission on the drivers side upper ear of the maincase. These are usually found on Boss, Cobra Jet, Super Conra Jet, Mach 1, etc. Some of the early K code Mustang Toploaders were stamped on the bottom center of the maincase with the complete VIN.

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