Check your rearend cushion and make sure it's not worn or loose if you haven't already done so. The rearend moves up and down as you go from park to drive or park to reverse.

When you say rearend cushion, are you referring to the differential mount bushing that is just forward and below the differential? If so I'll have to get under there and check it.

Yep. That's the one. Couldn't think of bushing

I checked out the bushing and it looks fine. I think Joel is right...I'll drop by and see the tranny guy and get some more info on what he put in this and post it here. I will say though it will sure break the tires loose going into 2nd.

I forgot to add that with my idle set at 600 rpm in gear... it's at 900 t0 950 rpm in park. Does that sound about right. I wish I could get the idle speed down a little in Park. Is this possible?

If it sounds like a clunk coming from the rear of the car, it's a good possibility that it's the cushion. Mine made noise any time I shifted from park or neutral into a forward gear or reverse. Cushion replaced, problem solved - hope it's that easy for you. LukesVette2009-06-10 08:15:07

I picked up a new set of differential cushions today, my Chevy Dealer had them in stock.... the ones that are in there look OK but it's hard to tell with out pulling them out so I'll go ahead and change them tomorrow, BKVETTE your right...the dealer calls them cushions and the catalogs I have call them bushings. Still haven't got to talk to the tranny guy yet so maybe this will help. I'll let y'all know.

Well after removing the differential cushions they were pretty bad. It's hard to check these without removing them. So put in the new ones. Helped quite a bit...still pretty hard shifting into drive but better... no clunk. Went to see my transmission man and let him drive me around a little. He said it is right were it should be...shifts into 2nd at 20 mph under light throttle and into 3rd at 30 mph. He said the shift kit firms up the shifts but the pressure is higher so going into gear is a little firmer. But I have managed to tune a little more and got the idle down a little more and now It's pretty good. Told you guy's I'd let ya know how it turned out...Thanks for the help. By the way, I replaced the cushions without removing the drive shaft. It can be done but if any of you guy's take out your drive shaft this would be one of those while your at it things.

Thanks BIO for letting us know. Glad you let us know what you found. We all learn from each others experience. Glad things are working out. The lower you can idle it down the better. I have my idle speed down to 500RPM and it don't bang too hard going into drive and reverse.

Another clunk solved!!!

Food for thought. thanks guys. I have similar issues with the green 78. Thought the tranny was toast.

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Jimmy B.
Just can't wait to get on the road again.

 
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