Product review (5 stars): Perfect for Our Tappan TGF336FWC. Save More Money by Moving the New Circuit Boards to the Old Case w/Overlay.
Once again, Amazon to the rescue!  My Bride came to me one morning asking if I had disconnected the oven or if there was a problem with the electrical circuit.  Nope.  It was this unit.  My first choice was to look for it on Amazon.  Just make sure this is the right timer for your appliance.

We have the Tappan Model TGF336FWC.  This is the correct unit for this gas range.  Don't use the numbers on the unit itself. Use the appliance model number.  If you do not find the correct timer this way, then select one of the products to order.  You will then get the box asking for your appliance model number.  It will then tell you if this is the right timer for your appliance. I originally ordered another one and had to return it for refund.  I was working from the numbers on the timer itself, none of which matches this number.

You can save some money by transferring the circuit boards to the old housing, if it is not melted or broken or otherwise unusable.  Otherwise you will have to buy the overlay - unless nobody in the house cares about aesthetics or knowing which button does what.  I used a small pry tool to move the retainer clips.  Just take your time and be gentle with it, because the unit consists of two circuit boards linked by a short ribbon cable.

I am probably making it sound more difficult than it is.  In less than 15 minutes I had changed housings and installed the replacement.