What are the symptoms if I may be so bold?
A lot of the time senders are not the issue. A stock 1979 with the NL2 dual tank option uses the dash switch to control the sender that's feeding the gauge. A lot of the time it's the $10 switch that's the problem.
It's fairly easy to troubleshoot. This is the Dual Tank Theory of Operation thread.
http://67-72chevytrucks.com/vboard/s...d.php?t=754061 Look at the post for the 73-80 systems.
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1959 M35A2 LDT465-1D SOLD
1967 Dodge W200 B383, NP420/NP201 SOLD
1969 Dodge Polara 500 B383, A833 SOLD
1972 Ford F250 FE390, NP435/NP205 SOLD
1976 Chevy K20, 6.5L, NV4500/NP208 SOLD
1986 M1008 CUCV SOLD
2000 GMC C2500, TD6.5L, NV4500
2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263
2009 Impala SS LS4 V8
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