Can anyone help me find out if my car is an origanal ss car? How can I find out what motor it can with? Here's the trim tag: ST69 13637 Kan 143853 TR 756 10 B PNT 11 C 03183

Nope, no way to tell on a Missouri built 69 unless you have the build sheet or protect-to plate or it still has the original big block with the VIN stamping on it.
If the color was originally Daytona Yellow or Monica orange it might prove it was an SS since those two colors were only available with the "SS" option.

How to spot a genuine SS Chevelle / El Camino (http://chevelles.com/shop/ss_ident.html#69)