EMD "SDP35" Locomotives: Data Sheet, Specs, Roster
Published: November 6, 2026
By: Adam Burns
The SDP35 is the steam-generator version of the SD35. Electro-Motive built 35 of them from July 1964 through September 1965, and the Seaboard Air Line took twenty, more than the other three buyers combined. The same 16-cylinder 567D3A produced 2,500 horsepower. A Vapor-Clarkson steam generator, model AR4125, sat in the rear of the long hood so the locomotive could heat a passenger train and still move a freight when the train was not there.
It was not a stretched frame. The length stayed with the SD35, 60 feet 8 inches on the specification sheet. What changed was the rear of the hood, closed up around the generator, and the work. The Seaboard still had mail and passenger trains that needed steam.
Seaboard Air Line SDP35 1115 with train 10, the northbound “Palmland,” at Raleigh, North Carolina, circa 1965. The print is not dated. No. 1115 is serial 29354, one of order 7734. Warren Calloway photo.
On this page: At a glance · The Seaboard order · Specifications · Production roster · Later numbers
At a glance
| Item | Detail |
|---|---|
| Builder | Electro-Motive Division, General Motors, La Grange, Illinois |
| Model | SDP35. An SD35 with a steam generator for passenger and mail trains |
| Built | 35 locomotives, July 1964 through September 1965 |
| Engine | EMD 16-567D3A, 2,500 horsepower at 900 rpm |
| Steam generator | Vapor-Clarkson AR4125, in the rear of the long hood |
| First and largest | Seaboard Air Line 1100–1119, 20 locomotives, order 7734, serials 29339–29358, July–November 1964 |
| The other buyers | Union Pacific 1400–1409, ten. Louisville & Nashville 1700–1703, four. Atlantic Coast Line 550, one |
| Seaboard Coast Line | The same 21 Seaboard and Coast Line frames became 600–620, then 1950–1970 |
The Seaboard order
The Seaboard diesel roster puts 1100–1119 on the passenger and mail trains that still needed steam. They were built as one order, 7734, serials 29339 through 29358, from July through November 1964. No. 1100 is serial 29339. No. 1115, the locomotive in the photograph, is serial 29354. The low short hood is the catalog Spartan Cab. These were not the high-hood freight units the Southern and the Norfolk & Western were buying at the same time.
Train 10, the northbound “Palmland,” was one of the assignments. The Palmland was the secondary New York–Florida train, with mail and express ahead of the coaches and sleepers, and the new hoods replaced the look of an E unit without replacing the need for steam heat. The same locomotives also went out on freight. SDP35 1111, with three Geeps, has train TT23, a southbound trailer train, at Boylan Junction in Raleigh.
Seaboard Air Line SDP35 1111 and a trio of Geeps lead train TT23, a southbound trailer train, through Boylan Junction in Raleigh, North Carolina, circa 1965. Warren Calloway photo.
The other three buyers came in 1965. The Louisville & Nashville took four, 1700–1703, serials 30454–30457, order 5691, in September. The Atlantic Coast Line took one, 550, serial 30531, order 7816, the same month. The Union Pacific took ten, 1400–1409, serials 30671–30680, order 7824, in August and September. Coast Line 550 and the Union Pacific ten kept an older fuel-tank profile. E8A 550 on the Coast Line is a different locomotive, one of the units bought from the Missouri-Kansas-Texas.
Specifications
Mechanical equipment followed the SD35. The differences that matter on this model are the steam generator and the service. Gear ratios and the loaded-weight table for the freight locomotive are on the SD35 page. This sheet does not give the SDP35 a separate top speed.
| Item | Figure |
|---|---|
| Years built | July 1964–September 1965 |
| Total built | 35 |
| Engine | EMD 16-567D3A, 2,500 horsepower, 900 rpm |
| Cylinders | 16. Bore 8 1/2 inches, stroke 10 inches |
| Length | 60 feet 8 inches, the SD35 sheet length. The frame was not stretched |
| Height, rail to top of cab | 15 feet 8 1/2 inches |
| Steam generator | Vapor-Clarkson AR4125 |
| Trucks | C-C Flexicoil, 13-foot 7-inch wheelbase, 40-inch wheels |
| Traction motors | Six EMD D67 |
| Main generator | EMD D32 |
| Air compressor | Gardner-Denver WBO |
| Air brakes | Westinghouse 26L |
| Multiple unit | Yes |
| Dynamic brake | Yes |
Production roster
Total built = 35. Each row is one builder order. A later renumber is not a second locomotive. Serial numbers, order numbers, and dates follow the Electro-Motive order list compiled by Andre Kristopans. The Union Pacific serial span is ten numbers, 30671–30680.
| Railroad | Road numbers | Qty | Serial numbers | Order | Date | Notes |
|---|---|---|---|---|---|---|
| Seaboard Air Line | 1100–1119 | 20 | 29339–29358 | 7734 | July–November 1964 | Later Seaboard Coast Line 601–620. 1115, serial 29354, is the Palmland photograph. 1111 is the TT23 photograph |
| Louisville & Nashville | 1700–1703 | 4 | 30454–30457 | 5691 | September 1965 | Later 1221 (2nd) and 1222–1224, then 4524 and 4537–4539. One career |
| Atlantic Coast Line | 550 | 1 | 30531 | 7816 | September 1965 | Later 1099, then Seaboard Coast Line 600. Older fuel-tank profile. E8A 550 is a different locomotive |
| Union Pacific | 1400–1409 | 10 | 30671–30680 | 7824 | August–September 1965 | Older fuel-tank profile |
Later numbers
The Seaboard Coast Line merger took effect on July 1, 1967. Seaboard 1100–1119 became 601–620. Coast Line 550, which had already been renumbered 1099, became 600. That is 21 locomotives. After the steam generators came off, 600–620 were renumbered 1950–1970. Those are the same frames. The block is on the Seaboard Coast Line diesel roster. The Seaboard numbers and serials stay on the Seaboard Air Line diesel roster, and Coast Line 550 stays on the Atlantic Coast Line diesel roster.
Four Louisville & Nashville units, 1700–1703, later ran as 1221 (2nd) and 1222–1224, then as 4524 and 4537–4539. Eight of the Seaboard locomotives, not the whole twenty, later ran as Louisville & Nashville 1290–1297. The Seaboard numbers tied to that block are 1101–1103, 1105, and 1107–1111. No. 7044 was retired before the renumber, and No. 1115 is not in the group. The Louisville & Nashville diesel roster carries both careers. The Union Pacific list keeps 1400–1409 in service from 1965 to 1985.
Related reading
- EMD "SD35" Locomotives: Data Sheet, Specs, Roster
- Seaboard Air Line Railroad: Map, Rosters, History
- “Palmland” (Train): Consist, Timetable, Route
- Seaboard Air Line Diesel Roster (All-Time)
- Seaboard Coast Line Railroad: Map, History, Photos
- Seaboard Coast Line Diesel Roster (All-Time)
- Union Pacific Railroad: Map, History, Logo
- Louisville and Nashville Railroad: Map, Rosters, History
Sources
- Andre Kristopans, “Road Switchers – 567,” the Electro-Motive order list preserved at utahrails.net. One Seaboard order, 7734, serials 29339–29358, July–November 1964. Louisville & Nashville order 5691. Atlantic Coast Line order 7816. Union Pacific order 7824, August–September 1965. The printed Union Pacific serial token on that list is short one digit. The ten units are 30671–30680.
- J. David Thompson, “EMD’s SD35 and related models – Original Owners,” for the same four buyers and the older fuel-tank profile on Atlantic Coast Line 550 and Union Pacific 1400–1409.
- Service Department, Electro-Motive Division, General Motors Locomotives, SD35 – SDP35 Operating Manual (La Grange: General Motors Corporation, 1964), for the Vapor-Clarkson AR4125.
- Seaboard Air Line, Atlantic Coast Line, Seaboard Coast Line, and Louisville & Nashville diesel rosters on this site, for 1100–1119, for 550 and 1099, for SCL 600–620 and 1950–1970, and for the Louisville & Nashville careers. The Union Pacific model list at utahrails.net dates 1400–1409 to 1965–1985.
- The SD35 page on this site, for the freight locomotive, the 360, and the loaded-weight sheet those figures belong to.
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