I'll just clamp.. I installed my '76 Duster dual exhaust (Jegs kit) and it's just clamped. Came out beautiful and has worked perfect. Better than the '74 Duster's and I paid to have that installed.
That is what is on Brian's Valiant, of course, he and his brothers had to run in to town and eat in it after he cut the old exhaust off. If I did that, every cop in town would stop me.