Two brands dominate the transmission-rebuild aftermarket: Sonnax (the upgrade specialist) and ACDelco (the OE-grade replacement). Most shops stock both. Which to use where depends on the failure mode you're solving.
SONNAX
Sonnax — Upgrade Aftermarket
When to choose
Engineering-fix-grade. Buy when the OEM design is the problem.
Valve body sleeve kits, oversize pressure regulators, heavy-duty servos, upgraded planets. Sonnax fixes engineering weaknesses that OEM never addressed. Higher cost per piece but solves comeback problems for good.
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ACDELCO
ACDelco — OE-Spec Replacement
When to choose
OE-grade. Buy when you need warranty-equivalent quality at lower cost.
Solenoids, sensors, gaskets, filters, friction packs. ACDelco is what came on the truck from the factory in most cases — replacing with ACDelco means warranty-equivalent on parts. Lower cost per piece.
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The healthy bench stocks BOTH. ACDelco for consumables and warranty-grade replacements. Sonnax for the upgrades that solve known weaknesses (valve body bore wear, pressure regulator, etc.). Our store stocks both — filter by brand on the collection page.