Installing a T5 into a 1978-1988 GM A/G Body
23. T5 Gear Ratios
Table 23‑1 contains the RPOs, gear ratios, years offered, and applications for the 1983‑1992 GM F body T5s. I found little information on the ML8 T5, but it appears to be the same as the MK5.
As a set (drive gear + driven gear), 5th gear is interchangeable with other T5s, but only within the World Class or Non‑World Class design. To maximize the overdrive in a World Class V8 T5 (MK6 or M39), the 5th gear set from an MB1 World Class T5 could be installed to obtain a 5th gear of 0.56:1. To maximize the overdrive in a Non‑World Class V8 T5 (MK6 or M39), the 5th gear set from an ML3 Non‑World Class T5 could be installed to obtain a 5th gear of 0.53:1. To minimize the reduction in rpm from 4th to 5th gear in either a World Class or Non‑World Class V8 T5, the 5th gear set from the MK6 T5 is the best choice at 0.73:1.
Table 23‑1: 1982‑1992 GM T5 RPOs, Gear Ratios, and Years Offered
| 1st Main | 2nd Main | 3rd Main | 4th Main | 5th Main | |||
| RPO | 1st Cluster | 2nd Cluster | 3rd Cluster | 4th Cluster | 5th Cluster | Engine | Platforms and Years Offered |
| MK6 | 32.00 | 33.00 | 30.00 | 24.00 | 31.00 | 5.0 L V8 | F Body: 1983‑1984; 1988‑1991 |
| 14.00 | 22.00 | 29.00 | 31.00 | 55.00 | |||
| ratios | 2.95 | 1.94 | 1.34 | 1.00 | 0.73 | ||
| M39 | 32.00 | 33.00 | 30.00 | 24.00 | 25.00 | 5.0 L V8 | F Body: 1985‑1991 |
| 14.00 | 22.00 | 29.00 | 31.00 | 51.00 | |||
| ratios | 2.95 | 1.94 | 1.34 | 1.00 | 0.63 | ||
| MK4 (1st design) | 33.00 | 31.00 | 29.00 | 22.00 | 27.00 | 2.5 L L4 | F Body: 1983 |
| 15.00 | 23.00 | 34.00 | 35.00 | 59.00 | |||
| ratios | 3.50 | 2.14 | 1.36 | 1.00 | 0.73 | ||
| MK4 (2nd design) | 33.00 | 31.00 | 27.00 | 22.00 | 27.00 | 2.5 L L4 | F Body: 1983‑1984 |
| 15.00 | 23.00 | 31.00 | 35.00 | 59.00 | |||
| ratios | 3.50 | 2.14 | 1.39 | 1.00 | 0.73 | ||
| MH3 | 33.00 | 31.00 | 27.00 | 22.00 | 27.00 | 4.3 L V6 | ST: 1987‑1989 |
| 15.00 | 23.00 | 31.00 | 35.00 | 59.00 | 4.3 L V6 | M Body/L Body | |
| ratios | 3.50 | 2.14 | 1.39 | 1.00 | 0.73 | ||
| MK5 (1st design) | 33.00 | 31.00 | 29.00 | 22.00 | 25.00 | 2.5 L L4; 2.8 L V6 | F Body: 1983 |
| 15.00 | 23.00 | 34.00 | 35.00 | 51.00 | |||
| ratios | 3.50 | 2.14 | 1.36 | 1.00 | 0.78 | ||
| MK5 (2nd design) | 33.00 | 31.00 | 27.00 | 22.00 | 25.00 | 2.5 L L4; 2.8 L V6 | F Body: 1983‑1984 |
| 15.00 | 23.00 | 31.00 | 35.00 | 51.00 | |||
| ratios | 3.50 | 2.14 | 1.39 | 1.00 | 0.78 | ||
| ML8 | 33.00 | 31.00 | 27.00 | 22.00 | 25.00 | 2.5 L L4; 2.8 L V6 | F Body: 1984 |
| 15.00 | 23.00 | 31.00 | 35.00 | 51.00 | |||
| ratios | 3.50 | 2.14 | 1.39 | 1.00 | 0.78 | ||
| ML3 | 32.00 | 31.00 | 25.00 | 21.00 | 25.00 | 2.5 L L4 | F Body: 1985‑1986 |
| 15.00 | 25.00 | 31.00 | 37.00 | 61.00 | 2.5 L L4; 2.8 L V6 | ST: 1985-1990 | |
| ratios | 3.76 | 2.18 | 1.42 | 1.00 | 0.72 | ||
| ML2 | 32.00 | 31.00 | 27.00 | 21.00 | 25.00 | 2.5 L L4 | ST: 1985‑1989 |
| 14.00 | 23.00 | 32.00 | 37.00 | 61.00 | |||
| ratios | 4.03 | 2.37 | 1.49 | 1.00 | 0.72 | ||
| MB1 (1st design) | 32.00 | 31.00 | 29.00 | 21.00 | 23.00 | 2.8 L V6 | ST: 1982‑1983 |
| 14.00 | 23.00 | 34.00 | 37.00 | 53.00 | |||
| ratios | 4.03 | 2.37 | 1.50 | 1.00 | 0.76 | ||
| MB1 (2nd design) | 32.00 | 31.00 | 27.00 | 21.00 | 23.00 | 2.8 L V6 | F Body: 1985‑1991 |
| 14.00 | 23.00 | 32.00 | 37.00 | 53.00 | 2.8 L V6 | ST: 1983-1985 | |
| ratios | 4.03 | 2.37 | 1.49 | 1.00 | 0.76 | ||
| MW1 | 32.00 | 31.00 | 27.00 | 21.00 | 25.00 | 2.5 L L4 | ST: 1989‑1990 |
| 14.00 | 23.00 | 32.00 | 37.00 | 51.00 | |||
| ratios | 4.03 | 2.37 | 1.49 | 1.00 | 0.86 | ||
| MB6 (1st design) | 32.00 | 31.00 | 29.00 | 21.00 | 25.00 | ST: 1982‑1983 | |
| 14.00 | 23.00 | 34.00 | 37.00 | 51.00 | |||
| ratios | 4.03 | 2.37 | 1.50 | 1.00 | 0.86 | ||
| MB6 (2nd design) | 32.00 | 31.00 | 27.00 | 21.00 | 25.00 | ST: 1983‑1984 | |
| 14.00 | 23.00 | 32.00 | 37.00 | 51.00 | |||
| ratios | 4.03 | 2.37 | 1.49 | 1.00 | 0.86 | ||
| F Body = Chevrolet Camaro; Pontiac Firebird L Body = Chevrolet Astro 4WD; GMC Safari 4WD M Body = Chevrolet Astro 2WD; GMC Safari 2WD ST = Chevrolet S-10, Blazer; GMC S-15 | |||||||