Internally Balanced 360 Cast Crank

dont know...never broke a 360 oem crank whether it was internally or externally balanced...sometimes I fell stupid and what to spend money uselessly and internally balance the crank...

my 71 demon and 71 duster are externally balanced...71 dart in internally balanced....also have an internally balanced crank in another engine...this crank is going in a short block to replaced the short block in the 71 dart...hence...already have balancer and flex plate for internally balanced crank.

Back in the 90s was spinning a oem 360 internally balanced crank 7500 rpm...stock rod broke...crank survived...and it had heavy trw domed pistons..