Exhaust knocking - engine mounts?

[The73vetteman]

I've had 2.5" dia pipes with headers on my '73 for years. Late last year I noticed that when I shut off the motor the right pipe would knock against the bottom of the hole thru the cross member.

When I started the car up last week (first time this year) there was no knocking at first but once everything was warmed up the right side pipe was again knocking against the bottom of the hole thru the cross member.

It's as though the exhaust is sinking lower in the car, so I'm wondering if this is an engine mount problem. If not, what else could it be?

John

 

[JohnZ]

Is the saddle bracket that goes under the trans mount still in place that supports the pipes just forward of the holes in the trans crossmember?