TH350 vs TH400 vs 700R4 – Real-World Comparison for Floor Shifter Installations
TH350 vs TH400 vs 700R4 – Real-World Comparison for Floor Shifter Installations
These three GM automatic transmissions remain the most common choices when pairing with a classic floor shifter. Below is a straight technical comparison focusing on the factors that actually matter for shifter location, lever length, tunnel clearance, and drivability.
| Spec | TH350 | TH400 | 700R4 / 4L60E |
|---|---|---|---|
| Overall length (bell to tail) | 27.75" | 28.25–28.4" | 30.75" (700R4) / 29.9" (4L60E) |
| Weight (dry, approx.) | 125–130 lb | 135–140 lb | 133–138 lb |
| Pan width (widest point) | 11.5" | 13.5" | 13.4" |
| First gear ratio | 2.52:1 | 2.48:1 | 3.06:1 |
| Final drive ratio | 1.00:1 | 1.00:1 | 0.70:1 (4th gear overdrive) |
| Torque converter lockup | No (unless aftermarket) | No (unless aftermarket) | Yes (1984-up) |
| Typical max torque rating | 350–380 lb-ft (stock) | 450+ lb-ft (stock) | 350–400 lb-ft (stock) |
Physical Fitment & Shifter Geometry
- Shortest overall length and narrowest pan → shifter mounting location falls in the stock floor hole on most 1955–1972 GM passenger cars and many hot rods.
- Standard 12", 16", and 23" straight or swan-neck levers typically clear bench seats without extensions.
- Minimal tunnel modification required in Tri-Fives, early Camaros, Novas, Chevelles, and most pre-’70 trucks.
- Pan rails are 2" wider and the case sits roughly 0.5–0.75" higher in the tunnel on many chassis.
- Driveshaft is ~0.5" shorter than TH350.
- Common result: shorter shifter levers (8"–12") are used to keep the knob at a comfortable height. Many builders prefer the short-throw feel on high-horsepower cars.
- Tunnel clearancing or mini-tubbing is frequently needed on 1955–1957 Chevys and early Fords.
- Tailhousing adds roughly 3" compared to TH350 → driveshaft must be shortened and crossmember often relocated.
- TV cable geometry must be correct for proper line pressure (critical for longevity).
- When clearance exists (1973–1987 GM trucks, 1982–1992 F-bodies, aftermarket frames), the 30% overdrive drop dramatically lowers cruising RPM.
- Shifter mounting location moves rearward slightly; 16"–23" levers are most common.
Typical Builder Choices by Application
| Application | Most Common Choice | Reason |
|---|---|---|
| 1955–1972 passenger cars, hot rods | TH350 | Easiest fit |
| 600+ hp street/strip | TH400 | Highest stock torque capacity |
| Long-distance cruisers, C10s | 700R4 | Overdrive + lockup converter |
| Original-appearing mild builds | TH350 | Cleanest installation |
| Big-block early cars with clearance | TH400 + short lever | Durability + aggressive stance |
All three transmissions accept the same bellhousing pattern (small-block or big-block Chevy) and share the same yoke/slip-yoke dimensions, making swaps relatively straightforward when length and tunnel space are accounted for.
Dedicated shifter kits with correct brackets and geometry exist for each transmission, ensuring positive detents and no missed shifts regardless of which unit is selected.
→ TH350 shifter kits → TH400 shifter kits → 700R4 / 4L60E shifter kits