I dunno but I think I have a bad bearing if there is one I got majjjjjjjjjjjor road noise at 75 my two front tires had seperation and i just got them replaced and I still have the noise. The whole car shakes it's so loud I can barely hear myself when i talk.

 

Sounds like a driveline issue. Need some more info. To answer your question though, no.

 

ok stock 99 ls1 on stock shocks and struts i did have an aluminum driveshaft when back to steel the one that came on the car made the sound worse, I'm on a bmr tq arm a relocation bracket solild mm poly trans mount 4:10 gears bald rear tires used front tires the bearings in the rearend have supposedly gone out.

 

it's more of a really really bad oscilation then anything

 

oh and it only happens from 70 to 80

 

The source of your vibration is the poly mount. There isa very good reason GM made the stock mounts all squishy and some filled with liquid. It was not because they were cheap to make in fact they are quiet a bit more expensive to make than a poly mount, It was to DAMPIN the driveline vibration they knew would exsist to variing degrees , So more some less but there.
Source is problably not the best choice of words. Better the REASON YOU NOTICE IT.

 

can i use a stock mount with a relocation crossmemeber?

 

I dont see any reason why you couldnt.

 

oh btw it wasnt doing this the whole time i noticed it after i replaced my tailshaft at 1st it wasnt that bad but has time grew on it became more pronounced. could it be my pinion angle also if a front wheel bearing goes bad wouldnt that set off the abs code?

 

oh ok i just wasnt sure, do you know what a harmonic hum sounds like? thats exactly the best way i can explain it, the sound I'm reffering to is there at lower speeds its just not has pronounced that I can tell.

 

Oh and it only seems to happen when I'm on the gas.

 

I still think its being transfered through the mount and very well may be a harmonic hum. since it more prevalent when in throttle I would think there may be some pinionangle issue also.

Little off track talking about harmonics. I once had a guy get a trans from me years ago, He installed the trans himself and a new exhaust at the same time,
Funny thing he he brought the car to me complaing of and anoying humming vibration at lower RPM in his car. Well I drove the car and sure enough there was a really bad hum/vibration feeling and sound. But it was not the trans it was the exhaust. But he would not belave me so i said leave the car I will figure it out, He was being kinda rude.
Well during the night I pulled both his mufflers and put two stock ones back on I had in the shop since we had done a little exhaust work ourselves here and there, Well he comes next day and i take him for a ride, All is quiet and smoothe no noise or vibration as he called it. Of course he was not happy that the exhaust was changed. But it was the only way to prove my point. I gave him his mufflers and charged him nothing and set him on his way.

This is not your issue I am sure and I imagine you have checked that the exhaust is not contacting the car chasis anyhwere but it just reminded of the story.