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Discussion Starter #1
This is in a new to me truck, from California. It's a 94 379 with a 425, 18 speed, with 411 on tall rubber. At 65 mph I'm tacking 1800rpm. I originally thought it was wrong. With an rto 18speed, I know believe this is correct. Which trans should I get to run 65 at 1600 rpm, the rtlo series? And I'm not opposed to running a 13 speed. And really don't want a double over. For some reason I can't get the road ranger road speed site to come up. Thanks Tony
 

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Discussion Starter #3
Thanks theakerstwo, but the road speed calculator won't work for some reason. I did look at trans ratio chart tho. Correct me if I'm wrong but the last two gears ([email protected]) on an rtlo trans, would both be overdrive. .87 for 17th and .73 for 18th. This must have what my old truck had. And the rto is just overdrive in 18th .87. Would there be any problems switching from rto to rtlo ?
 

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Discussion Starter #5
Would the low gear and reverse, be the same on rto and rtlo 13 speed? I can't figure that one out on the fuller ratio chart. I had a guy tell me with the rtlo I could go up one rear end gear ratio. From 411 to 390 and still have same low as the 411 with the rto 13 speed. Many thanks
 

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hey rocky:smile2: The easiest way is to change the differential and you can get it in junker for $750 and another for $500 if you put the RTLO cost around $2000 just to get 0.5 more fast and 150 rpm less this is nothing:frown2: , and you had another problem rtlo is 4 inches long and may you nned too chance the joke ,and need cut the mainshaft and center bearing :frown2: the best way put a 3.73 is best , much better than 3.70 for a 425 and rto 152 or 15618 those boxes are strong :surprise:
 

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Discussion Starter #8
Thanks pichu, it's a different truck. I'm buying a glider kit truck. I wanted 411 with 13 speed. They had one on lot with 390 and rtlo 13 speed. The salesman said the low would be same because the new 13 speed was lower geared than old one. They finally agreed to switch them to 411 for me. It's gonna be a dump truck so I want 411s. Hopefully I can get this deal done today.
 

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:frown2:hhmm !!!the saleman is simple a saleman he is wrong just for sale something>:) !!!!!a 13 RTO or RTLO !!!!DONT had lower !!I think in your case it would be better one of 15 ,15715 because 15 has 5 lower or like doyou had 15618 !!!those trasmissions had 5 lower speed perfect for botton dump or 10wheelers if you put a 13 your strees your clutch any time when you want to go so slow behing the alfalt machine :serious:
 

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Thanks pichu, it's a different truck. I'm buying a glider kit truck. I wanted 411 with 13 speed. They had one on lot with 390 and rtlo 13 speed. The salesman said the low would be same because the new 13 speed was lower geared than old one. They finally agreed to switch them to 411 for me. It's gonna be a dump truck so I want 411s. Hopefully I can get this deal done today.
First stay with the 3.90 and 11R24.5 tires. Use a RTLO18918B transmission. This will have a low gear ratio of 14.42:1 with the top gear being a 0.73:1 overdrive. The glider needs a modern electronic engine to communicate with the other computers in the truck properly

Now the real thing is you haven't stated what engine you're installing in the glider for your dump truck.

Most modern engines are designed to turn low RPM for fuel mileage. Yet have the power to pull gross weights of 80K Lbs easily. Unless you plan on going to very high gross weights, you don't need a 4.11 rear axle ratio. Even in off road conditions at 80K Lbs you don't need that gear ratio

Gear the truck for fuel mileage and the work being performed. Stop thinking about the old mechanical motors and the way they were designed to work versus how you want to set this truck up with a modern electronic engine.
 

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Discussion Starter #11
Thanks Haney, I went with 98 emission 60 series Detroit 500 horse power. The rtlo 13 speed with 411's. Half the time this truck runs on 55 mph roads. In 12th it tach 1500rpm at 55 mph. When on the big road in 13th it does 65mph at 1500. This seemed like best combo to me. If I could have got the 3406e 550hp I would have went with 390s.
 
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