The rag joint seems to have a different slightly looser feel compared to the Universal joint steering shafts in newer vehicles.
You could look into
Borgeson either a complete shaft or components... Or a Jeep steering shaft if you're on a tighter budget... YJ series I believe. Make sure to keep something similar to the collapsibility of the original... it's one of the safety enhancements on the squares compared to the 60's rigs and it actually helps in an accident.
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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
RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials...
Please include at least the year and model in your threads. It'll be easier to answer your questions.
And please let us know if and how your repairs were successful.