Shaking after gear install

I had my gears installed a week ago exaclty, and I let them break in for about 250 miles. Gears are FMS 3.73's and they do not whine at all. The only problem is that going over 80-100 miles (not to say 120-130 like test driving them today) the car shakes like a little 2 cents whore. It almost shakes like if the tires were messed up, even though they are 2000-3000 miles new.

I realized that right off the shop, in 5th gear it will do it very mildly and if you let off the gas it will reduce it noticeably. Is this a ****ty install? or is it normal that with bigger gears ur car shakes a little bit more. I mean is not the end of the world but going from my 3.27's in high speed I really notice the shaking more (even though if Im not mistaken I had a little bit going over 100).

Any help will be appreciated.

TIA!

Thx for your fast response guys. I checked on the weights and they are there, I might go by my friends shop for balancing and alignment anyways. Regarding the "dog bone" I do not know if they did this ( I was not the one that installed them), could you explain that to me, what is it exactly that way I'll go and check with the mechanic.

Thanks a lot.