The difference between the types the 6L6 appears in are:

• 6L6 is the metal cased 6L6. They have the same plate/screen ratings as the 6L6G/GA/GB. The 1614 and 1622 are premium versions of the 6L6 that are rated for maximum output and longer life.
• The 6L6G and 6L6GT have a large ST (Coke Bottle) shaped envelope. They have the same ratings as the 6L6GA/GB; 360 volts/19 watts plate and 270 volts/2.5 watts screen.
• The 6L6GA have a small ST (Coke Bottle) shaped envelope. They have the same ratings as the 6L6GB: plate rating 360 volts and 19 watts, screen 270 volts, 2.5 watts. The Y versions are more ruggidised and stronger types.
• The straight glass envelope version of the 6L6 is the 6L6GB. These have a plate rating of 360 volts, 19 watts and a screen rating of 270 volts and 2.5 watts.
• The 6L6GC is the latest version of the 6L6 tube. This version has a 500V/30W plate and 450V/5watt screen rating. If your amplifier calls for this tube, use it. The other types are probably not strong enough to survive in your amp!
• The EL37 is an european version of the 6L6. I has a tall ST (coke bottle) shaped glass envelope. I also can make a very good replacement for the EL34, but beware of the maximum anode voltage of 400V.
• The USA type 7581(A) is a industrial strenght version of the 6L6GC. It is said it is the USA equivalent to the British KT66. The ratings of the 7581 are about the same as the 6L6GC, the 7581A has little higher ratings.
• The 5932/6L6WGA are mechanically ruggedized tubes with huge brown bases and straight sided glass. They were produced only by Sylvania. They have the same ratings as the 6L6GA/GB. Great looking tubes!
• The 5881/6L6WGB was first developed by Tung-Sol for the USA miltairy. They have a sort of thick straight glass envelope. The ratings of the 5881 are 360V/23W for the plate and 270V/3W rating for the screen. Be careful using these tubes in an amp asking for 6L6GC, the 5881 simply might melt down in these amps!
• The 6N3C or 6pi3C is the Russian equivalent of the 6L6G. Very nice made and available at low prices. Great sounding tubes, even for EL34 replacements.

6L6GA(Y)

Type	Description	State	Brand	Number in stock	Price each (Euro)
JAN-CHS-6L6GA	Black coated glass, small ST shape, black plates, copper grid rods. Label on box is 6L6GAY, matched pair	NOS	Sylvania	1 pair	69.00 (pair)
JAN-CHS-6L6GAY	Black coated glass, small ST shape, black plates, copper grid rods. Label on box is 6L6GA, date 1943	NOS	Sylvania	1	29.00
JAN-CHS-6L6GA	Black coated glass, small ST shape, black plates, copper grid rods. Date 1943	NOS	Sylvania	1	29.00

6N3C or 6pi3C

Type	Description	State	Brand	Number in stock	Price each (Euro)
6pi3C	Black large base, straight glass	NOS	Russian NOS picture	7 pair 2 quad	24.00 (pair) 49.00(quad)
6P3S	Black large base, St shaped glass, black plates, very nice looking tubes, testing 46 and 53 mA	NEW	Dolam (Poland)	1 pair	19.00 (pair)

6L6G and 6L6GT

Type	Description	State	Brand	Number in stock	Price each (Euro)
6L6G	Large St-shape, Black plates, black coated glass	NOS/NEW	Sylvania	1 pair	90.00 (pair)
6L6G	Large St-shape, Black round plates, black coated glass	NOS	Fivre	1	48.00
6L6G	Large St-shape, Black plates, black coated glass	NOS	Brimar	1	48.00
6L6G / VT115A	Large St-shape, Black plates, black coated glass	NEW	Ken-Rad	1	38.00
6L6G	Large St-shape, Black plates, black coated glass	NOS	RCA	1	34.00
6L6G	Large St-shape, Black plates, black coated glass	NOS	Sylvania	1	34.00
6L6G	Large St-shape, Black plates, black coated glass	NOS	National Union	1	34.00
6L6G	Large St-shape, Black plates, black coated glass	NEW	Lafayette	1	30.00
6L6G	Large St-shape, Black plates, black coated glass	NEW	???	1	30.00
6L6G / CV1947	Large St-shape, Black plates, black coated glass, in Western Electrics 6L6G box, testing like NOS	USED	???	1	22.00
6L6G	Large St-shape, Black plates, black coated glass, center pin missing, loose base, testing like NOS	USED	GE	1	18.00

KT66

Type	Description	State	Brand	Number in stock	Price each (Euro)
KT66	Also labelled CV1075, with GEC green sticker still on glass	NOS	GEC	1	125.00
KT66	Black large base, glass shaped like the old GEC KT66, 2002 production	NNP	Sovtek picture	2 pair 3 quad	42.00 (pair) 95.00(quad)
KT66	Gold lion Genalex, made in Russia. Copy of the original clear glass KT66, factory platinum matched quads	NNP	Gold Lion	4 quads	129.50 (quad)

5881/6L6WGB

Type	Description	State	Brand	Number in stock	Price each (Euro)
6L6WGB / 5881	Brown base with white letters, in original cases, very rare old 5881 production, not new production	NOS	Tung-Sol	1	36.00
5881WXT	black base, straight glass	NNP	Sovtek	4 pairs 6 quads	23.50 (pair) 48.50(quad)

6L6GC

Type	Description	State	Brand	Number in stock	Price each (Euro)
6L6GC	New production	NNP	Tung-Sol	8 pairs 6 quads	28.50 (pair) 64.00(quad)

EL37

None in stock at the moment, please check back soon

5932/6L6WGA

None in stock at the moment, please check back soon

6L6GB

None in stock at the moment, please check back soon

1614

None in stock at the moment, please check back soon

6L6

None in stock at the moment, please check back soon

7581(A)

None in stock at the moment, please check back soon

1622

None in stock at the moment, please check back soon