Yup, i took the power out after 3 units failed on my 2001 g20, i bought a shorty flexible at wallmart, the antenna picks up reception by metallic contact. Unplug antenna pull out mast, cut base approx 2 inches, base will have a hole, put it in vise tap to size of adapter, that fits inside locking antenna nut, think mine was 1/4 20. The brass friction sleeve on old antenna mast, turn around put back on 2 inch piece as antenna will be base up, place back in power antenna housing ,install unplugged power unit back in vehicle ,reception will be better. I tried to get an adapter from motorola antenna end to japanese infiniti cable ,impossible unless you replace cable from radio out. best to adapt old unplugged power unit to aftermarket mast, no way would i splice factory cable , solder to adapt antenna leads, use as much factory parts as possible.
Wow... Just use the altima base and your favorite replacement. I went with the 350z mast. I did have to order a standoff from McMaster-Carr to lengthen the threads of the mast to fit into the base (Metric Aluminum Male-Female Threaded Hex Standoff 8mm Hex, 12mm Length, M5 Screw Size, 98952A261, Link Here). I bought a few different lengths and this worked out great after removing some meat with a dremel to skinny it up a bit.
^^ The rims were a work in progress there. They are now black.