From what I rember. Those quartz movement clocks were not ever used as original equipment on 113 or 107 cars, at least not the ones imported to the USA.
On the 1973 350SL the midddle hole of the 3 center dash vent outlets had a clock fitted there. This clock had similar bezel with the same diameter and movement as the earlier 113 clocks but didn't have the 113's studs on the back for a mounting bracket. The 107 clock had a rubber collar around the bezel that held it into the vent opening by friction.
Somewhere around 1974 when the existing stock of self-winding clock movements was used up both 107 and 113 replacement clocks were then made with a quartz movement, with studs on the back for 113s and without for 107s
107 clock with Kienzle self-winding movement.
In the 1974 450SL the clock (quartz) was relocated into the dial of the tachometer and all 3 of the dash holes had vents in them. On the USA models they were, not sure about other markets.
(edit) After I posted this I looked up the the replacement 113 clock on the EPC, it has the part number 100 542 01 11. The 100 prefix of the part number indicates that this part was made for the 600 series limousines (produced through 76) so the part was not made to be an exact duplicate of the original part, but one of a series of sequential upgrades to the parts used in production cars. So this could possibly be the reason the "quartz" was printed on the dial.
Al
