Click Here to reference Sportster VIN Information in the History section of the Sportsterpedia.
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This is the original 1977 XLH, XLCH frame (47012-76). The 78 frame was also used as a replacement for 1977.
The right lower frame tube was notched for the new (in 1977) gerotor style oil pump.
This is the 1978 XLH, XLCH frame (47012-78) and also a replacement frame for 1977 models.