An early system of car type classification saw the 3-car sets contain:

DMBS - A3 type motor coach
TC - D type trailer
DMC - B1 type motor coach

When TOPS was introduced each vehicle type was allocated a different class / sub class. Later the TOPS classes were rationalised and all simply became Class 104.

DMC

104/1

TS

160

DMBS

104/2

TBS

166

DMS

104/3

TC

169

DTC

140

Alterations to TOPS in the early '80s saw the need to avoid duplicated numbers, so 50xxx and 56xxx vehicles had to be renumbered to 53xxx and 54xxx respectively, keeping the last three digits.
Numbering Type Diagram Lot No. Seats Weight Formation Introduced Region Roof Lamp
50420 - 50423 DMBS 556 30290 52 31 tons 3-car 1957 LMR Yes
50424 - 50427 DMCL 558 30291 12 / 54 31 tons 3-car 1957 LMR Yes
50428 - 50479 DMBS 556 30293 52 31 tons 3-car 1957 LMR 50428 to 50443 only
50480 - 50531 DMCL 558 30294 12 / 54 31 tons 3-car 1957 LMR 50480 to 50495 (and 50529?)
50532 - 50541 DMBS 556 30296 52 31 tons Power trailer 1958 LMR No
50542 - 50593 DMCL (see below) 12 / 51 31 tons 4-car 1958 ER No
50594 - 50598 DMBS 557 30404 52 31 tons Power trailer 1958 ER No
56175 - 56184 DTCL 585 30297 12 / 54 24.5 tons Power trailer 1958 LMR No
56185 - 56189 DTCL 581 30405 12 / 51 24.5 tons Power trailer 1958 ER No
59132 - 59187 TCL (See below) 12 / 51 24 tons 3-car 1957 LMR -
59188 - 59208 TSL 583 30299 69 24 tons 4-car 1958 ER -
59209 - 59229 TBSL 584 30300 51 25 tons 4-car 1958 ER -
59230 - 59234 TSL 583 30302 69 24 tons 4-car 1958 ER -
59240 - 59244 TBSL 584 30303 51 25 tons 4-car 1958 ER -

ER DMCLs 50542-93 were composed of two different Lot numbers, one for each of the batches, and with each Lot number they were built to two Diagrams. The difference between each was allocation of the (non) smoking sections, and a 4-car set would have one of each Diagram.

50542 - 50562

Lot no. 30298

Diagram 580

50563 - 50583

Lot no. 30298

Diagram 559

50584 - 50588

Lot no. 30301

Diagram 580

50589 - 50593

Lot no. 30301

Diagram 559

LMR TCLs 59132-87 had two different Lot numbers, as they were part of two batches. All were to Diagram 582.

59132 - 59135

Lot no. 30292

59136 - 59187

Lot no. 30295

Original Set Formations

 

Power Trailers (15)

 

 

 

DMBS

M50532 - 50541

DTC

M56175 - 56184

 

 

DMBS

E50594 - 50598

DTC

E56185 - 56189

 

 

 

3-car sets (56)

 

    

DMBS

M50420 - 50423

TC

M59132 - 59135

DMC

M50424 - 50427

DMBS

M50428 - 50479

TC

M59136 - 59187

DMC

M50480 - 50531
 

4-car sets (26)

        

2 x DMCL

E50542 - 50583

TS

E59188 - 59208

TBS

E59209 - 59229

2 x DMCL

E50584 - 50593

TS

E59230 - 59234

TBS

E59240 - 59244