Rear Axle Measurements
Rear Axle Assembly drum to drum width:
| Year | Width | Spring mount eye to eye |
| 1928-1931 | 57.0″ | 49.5″ |
| 1932-1934 | 57.75″ | 47.5″ |
| 1935-1936 | 59.5″ | 48.25″ |
| 1937-1941 | 59.5″ | 48.5″ |
| 1942-1948 | 61.0″ |
NOTE: These width dimensions were measured with 1940 style brakes. Mechanical brakes may differ.
Stock Axle Length
| Year | Length | Number of teeth |
| 1928-1931 | 32.09 | 24 |
| 1932-1934 | 32.18″ | 18 (use 12 tooth spiders) |
| 1935-1938 | 32.85″ | 18 (use 12 tooth spiders) |
| 1939-1941 | 32.85″ | 16 (use 11 tooth spiders) |
| 1942-1948 | 33.70″ | 16 (use 11 tooth spiders) |
U-Joints
| Spicer # | NAPA # | Dimensions |
| 1310 | 369 | 3-3/16 x 1-1/16 |
| 1330 | 354 | 3-5/8 x 1-1/16 or 1-1/8 |
| 1350 | 331 | 3-5/8 x 1-3/16 |
Combination Universal Joints
| Spicer # | NAPA # | |
| 1310-1330 | 353 | |
| 1330-1350 | 448 | |
| 1310-1350 | 348 |
MPH = RPM * Tire dia (inches)
trans final gear * rear gear * 336