Need accurate 68 track width measurement!

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20+ Year Stangneter :roc</strong><span class=
Mar 17, 2003
946
20
49
Arizona
I've purchased an 8.8 TracLoc Explorer rear end with 3.73 gears for a good price and now need to give the shop the correct measurements for track width and spring perch placement.

I've searched and read untily my eyes bled and it seems that the track width for a '68 (distance between wheel mounting surfaces) is either 58" or 59 1/4".

Can anyone confirm the exact measurement? I want to keep the track width the same as stock. Thanks!