Yes, the bulb is in the head. The tube connecting it to the dash gauge is in a black plastic cover, and it should follow the front two injection lines out to the head. There should be a little clip that attaches to the 2 pipe holder for the front injection lines, and this clip holds that tube out of harms way.

The only way I figure to remove the whole thing, is unscrew and pull the bulb from block careful not to bend the tube. Remove tube from clip. Push tube into firewall a small amount. From inside the car, remove instrument pod, it just pulls out, far enough to unscrew speedo cable. Remove wiring plug and dash light pigtails (2). Now slowly pull pod out of dash area, hopefully with someone under hood feeding the tube and bulb into firewall. Then remove the gauge from pod. The gauge, tube, and bulb cannot be separated. Ron

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1971 220D, daily driver, new paint, 142K
1973 220D, low compression
1975 300D, back on the road! 166K
1971 220D, salvage, rear hit, engine excellent
1972 250, bad cam, but runs!
1971 230, engine stuck
1971 220D, low compression, rusty
1976 240D, salvage, engine excellent
1966 230SL, water in oil after rebuild