hey guys, i bought my 73 z28 about 6 months ago. Not too sure about the inner workings of the 406 it came with, all i know is its a flat top motor with a 520 lift cam and aluminum heads. it had a small oil leak, a little dope was leaking from her muncie m22 and it was shaking something serious when letting off the clutch in first gear only after it was at operating temp. it has been years since ive worked on hot rods and my knowledge is very limited so i decided to let a local mechanic do some of the work. i figured it was a rear main seal and the pressure plate maybe warped. after about a month in the shop and a new clutch pressure plate etc etc, it was still shaking only now it was in 1st and 2nd, so carried it back and he found that the flywheel was for a 350. so he put an external balanced flywheel for a 400 and now he says the car shakes bad when putting it in neutral at about 60 mph. he claims now that my bearings in the rearend are roaring and there is alot of play at the rear yolk and wants to replace the bearings and check the backlash. i had no problem with shaking whatsoever besides the low speed vibration from the clutch., does it sound like hes fishing for a problem? sorry so long and thanks in advance for any help.
p.s. this trip to the mechanic(which i wish i would have just learned on my own) is getting expensive