RG,
The gear selector is easy to adjust. Park the truck on a level floor. Place gear selector in park. Slide under the truck and loosen the adjustment bolt on the bellcrank rod which goes from the trans to the frame. Make sure the selector rod is free and can move inside the clamp on the bellcrank. Now rotate the bellcrank up, until you feel it drop into the park detent notch. Try to move the truck to make sure it holds in park. Now go into the cab, and make sure the gear selector lever is locked into the park position. Tighten the adjustment bolt, move the gear selector lever from low to park a few times, then back to park. See if the truck holds in park.

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