[DeTomaso] Techno Question: Stock half shafts torque tolerance

[cengles at cox.net]

Dear Forum,


                How much power or torque can one put through 40 year old 
stock half shafts?   Stock power only?  400 ft/lbs?  550 ft/lbs?

                Would there be any reason not to upgrade to Spicer half 
shafts?


                                Curious,  Chuck Engles