How do you tell if an engine is a factory rebuild? Check this picture out. There is a sticker near the back of the valve cover that says USA on it.

__________________
Currently driving a very clean 1985 300SD from the West Coast.

Its quite possible that its just a MB part sticker (looks like one) for a new valve cover if the old one cracked/warped or was damaged and they bought a new valve cover.

__________________
-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

i posted your picture with a red arrow, if it is a factory rebuilt unit, there will be a metal tag riveted to the block, it will be just above and to the left of the vacuum pump, you may need to clean a bit to find it,

Attached Thumbnails

 

__________________
1967 250 S
1967 280SE
1968 250S
1971 280 SE
1973 220
1974 280 S
1975 450 SEL
1976 220 D
1979 300SD
1983 300 SD
1985 230 TE euro
1986 280SL
1986 500 SEL euro
1986 190E 2.3
1990 300 SE
2003 C230 K
2004 C230 K
1987 560SEL
1987 300SDL now in canada
2005 C230
1998 C43 AMG Sold to DON
1993 190E 2.6
300TD Former daily driver Totaled
current:
R320 CDI
Ram 2500 Cummins

Also check for the same metal tag by the original stamped engine number, I have an engine from my old 190 that has a factory tag just under the stamped number, and it looks like they stamped lines across the original number.

__________________
Chris
64 190D R.I.P.
80 240D W/617 engine -for sale
82 240D -for sale

Where are those numbers located?
Maybe this guy has paper work for the motor exchange also....

__________________
Currently driving a very clean 1985 300SD from the West Coast.