200R4 or 700R4
Short answer: Both are overdrive autos; the choice is strength vs. fit. The 200-4R bolts directly to the Pontiac block and is nearly the same length as a TH400 (uses the TH400 crossmember), but it’s weaker — a 200-4R from a Buick Grand National or Monte Carlo SS is the stronger version. The 700R4 is stronger but needs an adapter (~$40) to bolt to the Pontiac block, sits ~2″ farther back, and won’t survive serious drag racing in stock form.
- Both need a shortened driveshaft (~$30), a shifter conversion kit (~$60), and ideally an external trans cooler. The correct (large) trans yoke from a TH400 car is needed (a 350TH yoke fits a 700R4).
- TV cable setup is tricky — you need the right bracket; a non-computer conversion kit (e.g., T.P.I. Tech, ~$70) makes it work without dashboard switches.
- Reality check: neither is anywhere near as strong as a TH400, so plan to have it rebuilt/beefed before use. Note: 700R4s came only in the Chevrolet bellhousing pattern (no factory B-O-P pattern); the Monte Carlo SS only had a 305/200-4R.
- Payoff: overdrive plus a lower first gear — one member’s 700R4 swap nets ~24 mpg highway behind a 310 hp 350 with a 3.4 gear, while still able to fry the tires.
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Content last modified: June 13, 2026 at 10:06 am
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