Hi Clarke,

https://www.askmehelpdesk.com/attachments/tools-power-equipment/24130d1251907949-john-deere-111-mower-belt-diagram-jd38oldeck.gif

It's the BOTTOM spring in this pic. I can't find a part # even at JD online. If nothing else, the dimensions would be helpful. Thank you! Steve

John Deere Idler Arm Spring - GX10120 (http://www.greenpartstore.com/John-Deere-Idler-Arm-Spring--GX10120_p_12472.html)

47759
Hi,
Pictured is an STX38 yellow deck. The spring you ask about is indeed the one the tensions the belt coming from the engine, but is not you deck.
Your deck is pictured here.
Peace,
Clarke

This is NOT my deck. I have TWO mower drive belts, one from the engine to the mower at the TOP of the idler spindle, and a second one from the bottom of the idler pulley to the TWO blades,(and there is a third one from the engine to the transmission) but the idler in question is only for the engine-clutch-to-deck, the SECOND idler and spring keeps tension on the blades' separate belt. The picture I included is indeed my deck, and the BOTTOM spring in the picture is the one I need, and no one knows what it is. Its diameter is about .875-1.00" and its length at rest is about 5" give or take. Sorry to be grumpy. It doesn't help that this mower is 30 years old.

Hi,
Then you do not have an L111, but instead have an older, by about 20 years, that had an 11 HP Briggs and a 38" deck. The picture you have should be correct, though I will certainly double0check myself. I have many unpublished pictures stored on multiple devices locally.
Peace,
Clarke

Hi,
Again, according to John Deere - Parts Catalog (http://jdpc.deere.com/jdpc/servlet/com.deere.u90490.partscatalog.view.servlets.HomePa geServlet_Alt)
The part number is M71684, no dimensions stated but it is a custom spring.
Peace,
Calrke

Hi Clarke,

Found it here:

http://www.greenpartstore.com/John-Deere-Tightener-Spring--M71684_p_9485.html

This is the guy. And I wouldn't have found it out there without your number. I had tried about 20 searches at that store, and that spring never came up. So well done, my man, I appreciate your being out there for me.

Steve