In Reply to: Re: rebuild kit posted by Jim on February 20, 2019 at 13:45:07:
In the "manual" section of this website there is a copy of the NAA manual. There is also the I&T FO-19 service manual. It list the piston size as 3.44" diameter x 3.60" stroke. Total of 134 in³. The block bore size for the sleeve is 3.65" I hope this helps.