if you park your rig and crank the stereo, say camping for the weekend, the bigger the better. i replaced my 650 cca with a 850 cca energizer and cost $89. no problem with the fit. i have always been a bigger is better fan as far as batteries go.
best bet is to measure your open space for the battery and throw an energizer in it.
i know you guys are not big on wal-mart batteries but i'm on my second truck but the same battery.

 

Well my hand got forced today.
Went to start the truck and had absolutely no juice. the fact that it started was a miracle in my mind. Cause once I got to work I was stuck again, after getting one of the mechanics to come out with a multimeter with me we determined my old battery was toast.

Since I was pretty poor earlier today *Before I was paid and found out about my nice little bonus* I couldn't afford the Optima I was considering. I'm now using a Stock sized 800 CCA Delco battery. Works like a charm so far

 

My 10 year old gold Die Hard is still going strong.