Popular Post j hancock Posted August 31, 2018 Popular Post Share Posted August 31, 2018 Between 1978 and 1979, Mack produced a total of four RD770's. Power was supplied by a Detroit Diesel 8V92 engine. This is the second unit built. 7 Quote JimIt doesn't cost anything to pay attention. Link to comment https://www.bigmacktrucks.com/topic/54172-1978-mack-rd770sx-tractor/ Share on other sites More sharing options...
h67st Posted August 31, 2018 Share Posted August 31, 2018 I like the wheelbase...just long enough. What does the SX signify? Quote Link to comment https://www.bigmacktrucks.com/topic/54172-1978-mack-rd770sx-tractor/#findComment-405237 Share on other sites More sharing options...
Popular Post j hancock Posted August 31, 2018 Author Popular Post Share Posted August 31, 2018 S ix wheel eXtreme service chassis = SX 4 Quote JimIt doesn't cost anything to pay attention. Link to comment https://www.bigmacktrucks.com/topic/54172-1978-mack-rd770sx-tractor/#findComment-405242 Share on other sites More sharing options...
blackdog2 Posted August 31, 2018 Share Posted August 31, 2018 SEXY.....? O & G had a lot and still use them on job sites moving trailers with 31/8 detroits aka 8-v-71 n/a . Quote Ed Link to comment https://www.bigmacktrucks.com/topic/54172-1978-mack-rd770sx-tractor/#findComment-405244 Share on other sites More sharing options...
Vladislav Posted August 31, 2018 Share Posted August 31, 2018 Wow! Something new. Thank you for posting the pic of the rare animal. Quote Никогда не бывает слишком много грузовиков! leversole 11.2012 Link to comment https://www.bigmacktrucks.com/topic/54172-1978-mack-rd770sx-tractor/#findComment-405247 Share on other sites More sharing options...
yarnall Posted September 1, 2018 Share Posted September 1, 2018 10 hours ago, j hancock said: S ix wheel eXtreme service chassis = SX I was shown a paper on Mack letterhead the explained the letters for the A models and it said X is for excavator. Mike. Quote Link to comment https://www.bigmacktrucks.com/topic/54172-1978-mack-rd770sx-tractor/#findComment-405269 Share on other sites More sharing options...
Red Horse Posted September 1, 2018 Share Posted September 1, 2018 I too thought "X"was "Severe Service" KSC?? Quote Link to comment https://www.bigmacktrucks.com/topic/54172-1978-mack-rd770sx-tractor/#findComment-405271 Share on other sites More sharing options...
kscarbel2 Posted September 1, 2018 Share Posted September 1, 2018 X doesn't have a meaning as many assume (I need to scan this when time allows). In the "Mack Highway Vehicle Unit Symbol Definition" page of the salesman's manual (dated 6-65): S - Truck, six-wheel [Note: truck, not tractor] LS - Truck, six wheel, weight-reduced version SX - Truck, six-wheel, off-the-road dumper or mixer X - Truck, four-wheel, dumper or mixer Remember, the first digit indicated gross vehicle weight. For example, R487ST, the 4 indicates a GVW of 30,500 to 56,000 pounds, and a GCW of 53,000 pounds. For example, R685ST, the 6 indicates a GVW of 30,500 to 76,000 pounds and a GCW of 65,000 to 76,800 pounds. For example, DM863SX, the 8 indicates a GVW of 31,000 to 100,000 pounds. 2 Quote Link to comment https://www.bigmacktrucks.com/topic/54172-1978-mack-rd770sx-tractor/#findComment-405283 Share on other sites More sharing options...
james j neiweem Posted September 2, 2018 Share Posted September 2, 2018 Black dog: How many Mack's does O&G still have? Quote Link to comment https://www.bigmacktrucks.com/topic/54172-1978-mack-rd770sx-tractor/#findComment-405327 Share on other sites More sharing options...
KKERGALL Posted September 2, 2018 Share Posted September 2, 2018 I would estimate at this time under twenty five? Will ask a friend of mine who runs the shop interesting question. Quote Link to comment https://www.bigmacktrucks.com/topic/54172-1978-mack-rd770sx-tractor/#findComment-405336 Share on other sites More sharing options...
KKERGALL Posted September 2, 2018 Share Posted September 2, 2018 " SX " indicates 58,000 lbs or above rear suspension. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/54172-1978-mack-rd770sx-tractor/#findComment-405337 Share on other sites More sharing options...
blackdog2 Posted September 2, 2018 Share Posted September 2, 2018 1 hour ago, james j neiweem said: Black dog: How many Mack's does O&G still have? A least 8-10 and town of Fairfeild has one same spec . Quote Ed Link to comment https://www.bigmacktrucks.com/topic/54172-1978-mack-rd770sx-tractor/#findComment-405338 Share on other sites More sharing options...
Popular Post blackdog2 Posted September 2, 2018 Popular Post Share Posted September 2, 2018 20- k rears 58-k 4 Quote Ed Link to comment https://www.bigmacktrucks.com/topic/54172-1978-mack-rd770sx-tractor/#findComment-405339 Share on other sites More sharing options...
Maddog13407 Posted September 3, 2018 Share Posted September 3, 2018 SX signifies sever duty. we had many B42sx's in the 60s that were rated up to 56000gross . sx doesn't mean 55,000 rears Quote Link to comment https://www.bigmacktrucks.com/topic/54172-1978-mack-rd770sx-tractor/#findComment-405361 Share on other sites More sharing options...
Popular Post Elephant ears Posted August 11, 2023 Popular Post Share Posted August 11, 2023 On 9/2/2018 at 11:23 AM, blackdog2 said: 20- k rears 58-k DM 685 SX tin nose drove a few of these Bulldog Mack’s dumps mixer packer trucks 237 with a mud stick 6 spd one of my absolute favorite Mack’s to drive 3 Quote Link to comment https://www.bigmacktrucks.com/topic/54172-1978-mack-rd770sx-tractor/#findComment-536807 Share on other sites More sharing options...
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