1985 El Camino hybrid driveshaft length?

[STF420@comcast.]

Looking for the c to c u-joint dim.?
85 El Camino hybrid LC2, 200R4, 8.5” GN rear
Originally 4.3L fuel injected.
Somebody installed a 305 v8 w/700R4 long tail (30.5”) 7.5” Rear, driveshaft is 58.25” c to c, already to short.

Thanks, Mike