Curious on what im working on

[Troyleedee]

Hello all, I've had this frame for awhile and starting to get some work done on it and was curious if anyone knew who made the frame or possible year? Thanks for any information

 

[45t]

Cat 400x. The serial # is on the leading edge of the engine plate and the first number designates the year. 9 = 1969, 70 = 1970, etc,