U Joint Zerk 70 Midget

Went looking for the grease fitting on rear u joint....nada.  Looked at the
owners manual and it is not on the lubrication list.  MossyVic shows a u
joint, with zerk, as the replacement part.  Were the zerks a victim of cost
cutting bean counters in later Spridgets?  (My Bug eye has em).  How long do
u joints last without regular lube?  I'll bet the answer to that is half way
between Florida and Philly,  on Interstate 95, on a very hot August day!