I've got two old RVs here that both had non-working fuel gauges. A 1978 Toyota Chinook and a 1977 Chevy Blazer-Chalet.
Both had bad sending units. I shopped around for the Toyota sender and found replacements prices pretty high (near $200). Japanese rigs use an odd-ball resistance range so nothing seems to be available aftermarket. 2-5 ohms when full and 110 ohms when empty.
I unraveled the broken wire and found out that it's 8 feet long and 33 gauge. Then did a search for special resistance wire that provides 110 ohms in 8 feet (13-14 ohms per foot). I bought a roll of 33 gauge Nichrome 60 type resistance wire. $6 for a 100 foot roll. TEMCO part # RW0288. I rewound it and all is fixed.
Great info, thank you!