The Spicer 5756B 5-speed is listed as a "close-ratio" and was only available when the 2-speed rear and 427 engine were ordered. It's ratios are as folllows;
1st = 6.50
2nd = 3.52
3rd = 1.93
4th = 1.18
5th = Direct
Reverse = 6.88
Here's the ratios for the Spicer 3053A
1st = 6.00
2nd = 3.31
3rd = 1.89
4th = Direct
5th = 0.85
Reverse = 5.90
Mike B
