I have a 2003 GMC Yukon XL 4x4 with the 5.3L Flex Fuel motor. 3 weeks ago it was throwing lean codes for both banks so I took it in and had the intake gaskets replaced(old ones looked like ****). Just yesterday when I fired it up the battery light came on and the dash read "Battery Not Charging" then right after it said "Service Brake Booster". I took it to an O'reilly's and they said the battery is fine but the alternator is only putting out 11 amps. Could a bad alternator cause both those issues? I understand that electrical problems like alternator/battery can cause all types of codes but there was a noticeable vibration in the brake pedal after the "Service Brake Booster" warning came up. Another issue, now that I'm alternator shopping every site I pull up is showing 105 and 145 amp alternators for my vehicle saying both will fit. I contacted a couple GM dealership parts departments (in Hawaii since they're the only ones open this late) and had 2 tell me to get the 145 and 1 said the 105 is the standard one. My local Advance Auto can get me the 105 amp for $89.99 tomorrow but can't get the 145 amp one for 4 days and it's $149.99. Could I get away with the 105 amp or does the truck call for a 145? I can't find anything online that helps me. Thanks!!