I need all of them or the old silencer to work from, you cannot take a guess at the measurements.
To put this into context. I have wasted hundreds of hours buying in and modifying exhaust silencers. I have now sourced all the mild steel parts which are laser cut to put them together myself in 4″, 5″ and 6″ dia round silencer box. I then bend, cut and put whatever size and length inlet and outlet pipes you need in and TIG weld the whole thing together. I actually had a company that had a go at doing it for us but they could not cope with all the variations and apart from that the welding was crap.
Regards Mike