I have had both the red and yellow top in my 4Runner(not at the same time)... I think I ran the red one in to the PS pulley on my rig.. the red top have a little more voltage and a little more CCA.. matter of fact my red top was proven to have something like 1300 CCA after a year of service.. I think that is 400 more than the manufacture claims.. I have a yellow top in there now, I haven't had the CCA checked since i bought it but it does fine.

One thing you might take into consideration is that the red tops have a 3 year FREE replacement while the yellow only have one year..

the blue tope are the same as the yellow or red depending on the part #.. I think the blue top with the dark gray housing is the same as the red top. and the blue top with the light gray housing is the same as the yellow top.. they just have screw on terminals one them..

HTH,
RAZZ