My odometer died shorty after picking up my '78 300d at ~146,000 miles, and a few months later, the speedometer then died. I am pretty sure the cable is broken, but have not pulled it as of yet.

My question is, are there any options either electronic or analog that would be feasible (and more reliable)?

The speedo cable is easy to replace and not expensive. The repair for the odo pot metal gear is pretty easy and there is info available with pics. You will need to search for it though unless somebody else provides you with the link.
Can't imagine not going back with the stock setup. I've repaired 3 of these and it isn't that difficult.
If you want it rebuilt then I believe Tyler had his redone somewhere and may chime in.
Electronic???? Please...........

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Jimmy L.
'05 Acura TL 6MT
2001 ML430 My Spare

Gone:
'95 E300 188K "Batmobile" Texas Unfriendly Black
'85 300TD 235K "The Wagon" Texas Friendly White
'80 240D 154K "China" Scar engine installed
'81 300TD 240K "Smash"
'80 240D 230K "The Squash"
'81 240D 293K"Scar" Rear ended harder than Elton John

Yup, tried to do it myself, but pulled out the pin that you're not supposed to pull out.

So, I sent it in. About 80 bucks later Norm had a functional odometer. Very nice guy, and a less than 2 week turnaround.

http://www.speedometer.com/

Digital? Yuck.

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1985 500SL Euro w/ AMG bits 130k
1984 300SD Turbodiesel 192k
1980 240D Stick China 188k
2001 CLK55 AMG 101k
2007 S600 Biturbo 149k Overheated Project, IT'S ALIVE!!!

Not talking digital. I would never put one in anything I drive. But, having an electric sending unit going to a gauge would be nice.

If you replace the cable and fix the gear it will last another 30 years.