Assuming you're referring to a KA head here. There are differences between fwd and rwd KA heads, which is most likely what you're seeing in regard to the difference in number of JOURNAL caps.
Short answer; no you cannot use a fwd KA head on a RWD application like the 240sx. Its also possible youre finding a frontier truck head. You CAN swap between s14 and s13 240 heads, provided you swap to the appropriate valve cover for that s13/s14 head.
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The S13 and S14 KA look very similar, save the location of the 3 valve cover bolt holes. It may help if you link to pictures of the heads in question and let us know what your application is.
S14 240sx KA head;
Altima KA head (note the spot for the distributor directly off of the camshaft);
truck KA head (5 caps);
