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Engine - New Longblock 6.5L Center Mount Turbo ATO
Engine - New Longblock 6.5L Center Mount Turbo ATO

Engine - New Longblock 6.5L Center Mount Turbo ATO

On sale: $7,952.23
Custom Drop Ship Delivery
Part Number:6504053ATO
  • Condition:New
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Assemble To Order (ATO)
Engine Preparation
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I understand that this product does not include a warranty.
New AM General - GEP Optimizer ™ 6.5L Diesel Engine - Center Mount Turbo Van & H1 Hummer

This is the latest version of the 6.5L engine still produced new today. These are build-to-order engines in that your engine is run down the assembly line after order. Unfortunately, they are not built ahead of time and stored. Standard lead time to delivery is approximately 6-8weeks, sometimes less depending on assembly plant's load.

This engine directly replaces engines in 1996 - 2002 Savanna G2500/3500 6.5L Turbo Diesel center mount turbo applications, such as those found in full vans, cab and chassis for box vans and bus configurations.

This engine also directly replaces engines in 1996 and up H1 Hummer 6.5L Turbo Diesel. This offering applies to the H1 Hummer Civilian application (non-military).

Features & Included:

  • Engine Longblock Assembly (engine, timing cover, balancer, covers, pan, lift brackets, as pictured)
  • Forged Crankshaft (we've known this since 2019 just didn't publicize this to our competition)
  • Block Heater (120 volt)
  • Oil Filter (filter and filter fitting)
  • Oil Pressure Sensor/Switch pre-installed
  • Filled with 15w40 Break-In Oil.
  • HD = Heavy Duty Emissions Rating
  • Diamond Pre-Combusion (largest) Cups for higher HP ratings
  • Cylinder Heads with 60 degree intake manifold bolt angle.
Engine features all metric fasteners, so if replacing a Pre-1999 model Engine, please inquire after purchase about a metric fastener kit after purchase necessary for replacing your existing engine (will need to know year/make/model). This is only available to customers who purchase a Longblock here. Approximately $95 shipped.


These new long blocks carry no warranty. The manufacturer provides no warranty on these engines. Unique Diesel provides no warranty on these engines. Warranty coverage is not an option on these engines and is a term of the manufacturer. We are being up-front about the limitation which is more than can be said for other potential sources.


This item is available for purchase via traditional payments and credit cards with courtesy fee for USA customers. Must select Credit Card Courtesy on this product if you will be using a credit card on the final checkout page. International customers can not use a credit card for this item, please request the use of a traditional checkout method.

Both USA customers and International customers can utilize the optional traditional payment method for this product which can save money (no Credit Card Courtesy Fee). Please contact customer service for access and guidance in using traditional checkout method for the store.


Select the shipping option that meets your need. Items with shipping amounts are for Continental USA shipments only. Flat rate shipping is provided as courtesy and we cannot provide alternative shipping estimates, please select an option provided. We do not provide quotations for export shipments outside of the USA, but will ship to your USA located freight forwarder using the rates provided. Please source a capable Freight Forwarder in the USA that we can ship to, they can then ship to your country. Take note of the engine preparation requirement for export engines where the forwarder uses Air Freight.

In person production plant local pick up is an option that is available for those within driving distance of Franklin, Ohio USA. Only available to the named purchaser and by appointment. Coordinate this with customer service when item is ready for pickup. If item is not picked up and requested shipped after making this selection shipping can be arranged but with separate payment and a brokering fee applies.

Shipping will be performed in a secure shipping crate, exactly as pictured. Engine is safest shipping in this method!

Engine Preparation Options

If unit is being shipped via Air Freight (typically international) the engine must be free of oil, new engines come with break-in oil in the pan, so engine must be un-crated and drained of oil and a new filter installed (that is dry). This requires being sent to Unique Diesel for processing making it not possible to drop-ship from factory, this is part of the cost associated with this option.

Addition of timing tab for mechanical engines. The factory cannot modify this assembly as it's intended for electronic engines. We can optionally add the mechanical timing tab to the front of the engine's timing cover with special tooling and have it match TDC for timing with timing lights, We do this and add the plug in the timing cover to delete the crank sensor opening. This makes the engine have to come to us instead of being able to drop-ship. This is part of the expenses figured into the cost of the option.

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