79 blazer clapping noise on exceleration on highway

[exodus138]

my 79 blazer has been running great with the excepion of a exhaust leak i have a 350 in it. however recently when im on the freway and giving it gas i hear a clapping noise on exceleration and have ben noticing small backfires from yhe exhaust. i havent drove it since because i dont want to damage anything. now my question is would this clapping/ tapping noise be from the exhaust leak or is it a valve problem. whn i let off exceleration it doesnt tap. any suggestions?

[Lt.Del]

my truck did that, found out it was the heat shield of my catalytic converter being hit by the driveshaft.  The tranny mounts were broke and my transmission was moving around and the driveshaft was hitting the heat shield. 

[exodus138]

im gna check that when i get home i had a t350 installed a couple months ago! thanks! i hope it is that easy!

[Lt.Del]

well??  find out n e thing?

[exodus138]

thank u so much it was the drive shaft knocking on the cat had it remounted and shes up and moving! faster stronger! thanks so much

[Lt.Del]

anytime.  glad you got her figured out.  You probably had a loose exhaust swaying into the driveshaft, versus my loose tranny swaying into the cat. 

[k5blazerfan]

cut the cat off fixes any future problems with the cat there lol