The 80 300D does not have the spring at all. The top of valve cover is completely different
on 1981 and back. No transmission cable at all no cruise parts.
The cruise control on older cars is a different system.

But on the the 1983 300SD - Just drove 75 miles. LOVE IT without
the spring.

I should also mention the the two stacked up 2/3 valves were removed completely and all vacuum
plugged off. I did this after advice here that said on newer cars those valves
are for EGR and not trans shifting.

So removing the spring coimpletely (no cutting required, I got a nice smooth pedal.

And my cruise control works, possibly even better because it is not working so hard.

Whole job took maybe ten to 15 mintues.
Carried the spring with me today - just in case.

Anyway - I recommend removing the spring.
The injection pump and pedal have springs that will handle pulling the throttle back.

Use this advice at your own risk, I cannot be held liable.

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80 300D 340K Owned 30 yrs
83 300SD 440K Owned 9 yrs - Daily Driver 150mi/day
02 Z71 Suburban 117,000
15 Toyota Prius 2600 miles
00 Harley Sportster 24k
09 Yamaha R6
03 Ninja 250

I went at it again for a few this afternoon and got the pedal out. It looked fine. I ordered a new bushing for kicks...$2 at the parts counter. I'll put it in later.

Pedal mount piece of steel is rusty - time to get on that :-)

I also removed the spring on top of the valve cover. It made shockingly little difference not having it there. Ill need to collect more data on that.

My next move is to take it completely apart, re-set the linkages and clean everything really well.

Should I use Type F ATF, or is Dexron III OK for linkage oil?

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'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car