So I have a 1970 Chevelle SS 454 but I can't tell if it is an LS5 or LS6 it has the LS6 radiator support and the 3:31 rear end its an auto with LS5 tach and gauges

Does the air cleaner have a HP rating sticker on it? LS5 = 360. LS6 = 450. The LS6 had solid lifters but the LS5 had hydraulic lifters.

https://heacockclassic.com/articles/the-best-muscle-car-1970-ls6-chevelle/

Wikipedia was no help and there is no engine but we do have the rear end

get the numbers of of the front of the motor , left side by water punp LS5 360 Manual CRT 2,763 LS5 360 Manual CRU * LS5/M40 360 TH-400 CRQ 2,197 4,960 Total LS5 Engines 4,298 Total LS5 Chevelles ** 0,662 Service Engines 87% of total LS5 engine production went into Z15 Chevelles in 1970. ** This number of LS5 engines does not include the 3,833 that were sold with the Z20 Monte Carlo SS454 option with suffix code of CRN. LS6 450 Manual CRV 3,525 LS6 450 Manual CRX * LS6/M40 450 TH-400 CRR 1,923 5,448 Total LS6 Engines 4,475 Total LS6 Chevelles 0,973 Service Engines

Try this site, it has tons of info on the 1970 Chevelle http://chevellestuff.net/1970/70ss.htm