As a quick recommendation if you dont read any further do NOT, I repeat do NOT give US Engine Production your business, money, or time in any way or form, they are either incompetent and lazy or intentionally dishonest based on the length of time they have been in business I would have to assume they are the latter. We purchased a remanufactured Caterpillar 3126 diesel engine from them early this year (Feburary, 2020). The engine was received after a reasonable length of time and was strapped down and palletized as would be expected from a heavy, medium duty engine. Installation went okay and the engine itself ran well and had no issues after our initial 150 break-in miles. So, I would give the initial experience 5 stars. Returning the core long block for credit was where the nightmare began. After waiting for a core pickup for an extended length of time, the old engine was picked up and delivered back to them. This was an engine core that was running, driving, and working well with no issues other than excess crankcase pressure and low compression on cylinder #2 after an initial compression test. Once they received the core they denied a full core credit ($2,500.00) stating the cylinder head was bad (had cracks, couldn't weld or fix) and another issue existed with the block (injector cup damage and that the block was "destroyed"). We initially requested pictures of the damage or wear with no response or acknowledgement for the next 30 days. Our only successful phone conversation in mid-summer ended with them agreeing to refund a partial core of $800 due to the unsubstantiated damage but we would only accept the partial payment with photo proof of damage. This was only a verbal agreement from them, nothing was given in writing by them. They sent timely and frequent emails to us for payment and initial order, but ignored us after core return. After FIVE more months of ignored emails, non-returned phone calls and contact attempts, on October 29th 2020 the manager (Eddie Bonilla) responded in an email and I quote; Pitted Cylinder head, even if you surface the cylinder head there wont be a head gasket to overcome the surface, also the main cap off the block isnt good. What happened to the cracked cylinder head, now it's pitted? With the refusal to send a SINGLE picture or any hard data to substantiate their claim regarding internal damage, this was completely unacceptable as the only email communication received from them about refusing to refund $2500.00! After initial purchase was complete, the staff was consistently rude, abrupt, and downright irritated to be asked about this during the very short phone call about this issue. As a very busy and successful light and medium duty production automotive repair shop, we have over 25 years of experience in working with dissatisfied customers and this hits every single red flag for how NOT to respond to a dispute. The poor review quality and quantity across multiple platforms either means you attract a lot of angry, unreasonable people or possibly you have very poor customer service and business practices. I have never dealt with ANY remanufactured drivetrain company (Jasper, Jet, LKQ, Motorcraft, ACDelco, etc) that has such a screw you and go away attitude over a core charge that is nearly 50% of the entire engine cost! We will be reporting them to the NY Better Business Bureau which they claim to hold an A rating with, hopefully if someone reads this it will prevent them from wasting their year chasing down a shady company. User's recommendation: Stay away and buy from a reputable engine rebuilder that will respond and treat you fairly.