Are There Any Online Resources For Information On Heartfield Instruments? Yes, we've discovered a great resource for information on Heartfield Guitars. Related articles The Who, What and Why of Heartfield. Heartfield Price Lists 1989-1992 How can I find out how old my instrument is if it uses an odd or non-standard serial numbering scheme Stratocaster® Service Diagrams How can I find out when my Mexican-made instrument was manufactured?