Custom Electric Service Inc., out of Ohio is by far one of, if not THE best H.O. alternator company on the market right now. 90% of the major car audio guys prefer their alternators. Jonathan Patrick is the guys name who is probably the most involved employee pertaining to automobile applications. They offer a lifetime labor warranty on their alternators, and in most cases, if you get a different vehicle, you can trade in your current CES alternator for a heavily discounted new alternator for your new vehicle. These are the prices that I got: Slot wounds are 270 amps for 245$, 300 amps for 325$. These are a little older technology but proven performers. Slightly less durable than hairpins, and a little lower charging voltage in most applications as well. 250 amp small case hairpin is 320$, 320 amps is 385$. These are great for smaller builds running lithium or caps. The regulators and rectifiers are tough enough to withstand the abuse a little better than the slot wound units listed above. 270 amp large case hairpins are 375$, 370 amps is 495$. 390 amps are 595$. These are the most durable unit and second best at idle. They have larger rectifiers and normally around the 200 amp range for idle output. The 390 amp is usually around 170-180 amps at idle and comes in a billet machined aluminum case. These large case units have the only 80 amp diodes large case twin plated rectifiers available on the market. 300 amp XL unit is the absolute best at idle. These are our newest line of alt that have 230-240 amps hot at idle rpm on most applications. They’re also incredibly durable with big 100 amp diodes on finned rectifier assemblies. These units are 605$. Every alternator is build to order. 2-3 weeks is average for build time right now. Lifetime warranty at parts cost. 6 months no questions asked no defect guarantee. All of our prices are shipped and include one decal. Around last thanksgiving, I bought my dad a 270 amp large case hairpin for my dads 91 C3500HD dump truck with electric-over-hydraulic dump pump. with the stock alternator, dual batteries, and big 6 upgrade with 1/0 wire and nothing in the bed, the digital voltmeter would dip down and stay at 10.xx volts at idle. After the installation of the CES alternator, we decided to lift 5k# of salt and see what it did. it would dip down to 12.5 volts, and then very quickly and steadily go back up to 14.2 volts while lifting. Jonathan told me that the alt that I chose will do very close to 200a at idle. When lifting the 5k# of salt, I had an amp clamp on the pump's 1/0 while lifting, and it was pulling 220 amps. I did have to make the AD244 fit, because the truck had the CS130 (IIRC?). All I had to do was trim the alternator bracket a little, but Jonathan walked me right through it and ensured me it was fine. I probably have 30 messages going back and fourth between us. The customer service that they provide is second to none, and I cannot recommend them enough. You'll definitely want to do the big 3 on each of your batteries, also. I bought this crimper from Amazon: https://www.amazon.com/BETOOLL-Hydr...r&qid=1558440557&s=gateway&sr=8-1-spons&psc=1 All of his terminations are crimped, and then I bought mesh wire braiding from Ebay, and "terminated" the ends with adhesive lined heat shrink tubing. I am not using fuses on the big 3 for either battery. This is also a plow/salt truck, so I wanted as little connections as possible just to minimize the chance of them coming loose. The cables are secured very well and I made sure that there is no way that they can short out.