Shift Improver Kits - Buick, Chevrolet, GMC, Olds, Pontiac - 1968 to 1981 TH-350 and M38 Application: 1968 to 1981 TH-350 and M38 (for TH-350C use Transpak # 30235) Recalibrate your automatic transmission for optimum performance and extended life! Provides crisp shifts on any stock automatic transmissions. Elimination of soft sluggish shifts, shift overlap, and excess wear on clutches and bands due to slippage. Improves transmission life. Transmission removal not required. The B&M Shift Improver Kit the easiest way to get the stout performance you've always wanted out of your automatic transmission - and you get two modes of performance to select from: Heavy Duty, or Street/Strip. It's our least expensive and simplest to install kit. All you need are a few dollars and some hand tools! In the space of an afternoon, you can turn your transmission into a B&M-tuned unit! Just ask the thousands of satisfied customers that have installed one in their transmissions! Stage 1 - Heavy Duty Firm positive shifts without loss of driver comfort for improved performance in all street vehicles. Recommended for regular passenger vehicles. Stage 2 - Street/Strip Provides very positive shifts for high performance street use or for competitive events. This model is for the enthusiast who wants the hardest, quickest possible shift.
Features:
- Recalibrate your automatic transmission for optimum performance
- Select the mode that best suits your application
- Improves transmission life
- Transmission removal not required
Most stock automatic transmissions won't downshift into low gear above 15 mph, and automatically upshift at a predetermined speed no matter what gear you're in. With the Transpak, you can downshift at any speed, and you can hold the transmission in first gear to any speed that you want! This is an asset when you've got a modified engine, and you want additional RPMs, or you're towing a trailer or driving heavy loads downhill. Stage 1 Heavy Duty - For street rods, normal passenger vehicles or other heavy duty use. Firmer shift feel but not harsh. Improves transmission performance and life dramatically without loss of comfort. Normal automatic operation when in "Drive". Stage 2 Hi-Performance Street - For full performance street use. Essentially the same as Heavy Duty mode except shift is much quicker. Retain full automatic features and standard shift points with selector in "Drive".
⚠️ California Proposition 65 Warning:
This product may expose you to chemicals known to the State of California
to cause cancer or reproductive harm.
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Price Match Guarantee:
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We reward enthusiasts who trust us with their major projects. Use these tiered codes at checkout to apply instant savings to your order:
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Fitment Guarantee:
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Avoid the headache of the wrong part. If you are unsure about compatibility, contact us first. If we verify the fitment for your vehicle via email and it doesn’t fit, we will handle the exchange at no cost to you.
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Secure Shipping:
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Please inspect your order immediately. Damage must be reported within 48 hours. For freight/LTL items, if you cannot inspect the contents immediately, please write "Subject to Inspection" on the delivery receipt before signing.
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Flexible Returns:
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Unused items in brand-new, original packaging can be returned within 30 days. While standard refunds incur a 25% restocking fee, we will waive this fee entirely if you choose store credit or an exchange for your next upgrade.
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Exclusions:
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To ensure every customer receives brand-new, untampered components, parts that have been installed, modified, or used are non-returnable. Custom builds, special orders, and wheel/tire packages are considered final sale.
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Fitment Guarantee
Fitment guides and tools are helpful—but your car is unique! Some trims and options aren’t always listed, so if you want 100% confidence that a part will fit, our team is happy to double-check for you. We take the guesswork out of your purchase by standing behind our expertise.
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If this product doesn't list your specific vehicle data, simply reach out to support@autohousesupply.com. We will manually verify compatibility for you.
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Our Promise:
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