Yes, there are different sizes, but really any PLCC will work, as the length is usually the same. I've done some comparisons here for you, price and MCD (MCD = MilliCandellas, the more the brighter)
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white is a tad narrower at .90$ a piece MCD unknown
http://www.goldmine-elec-products.com/prodinfo.asp?number=G16010
where as blue is standard size at .45$ a piece MCD unknown
http://www.goldmine-elec-products.com/prodinfo.asp?number=G13706
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eled.com has the most variety of any site:
They call them PLCC2 and have two different sizes under the "Single Color - Top Emitting - PLCC2" category
PLCC2 - 3.5mm x 2.8mm LED white = (150mcd) = 0.40 / PCS, high brightness (800mcd) = .68 / PCS
PLCC2 - 3.0mm x 2.0mm LED white = (150mcd) = 0.40 / PCS, high brightness (800mcd) = .76 / PCS
http://www.eled.com/category.asp?catalog%5Fname=LEDs&category%5Fname=Single+Color+SMD+LED&Page=1 Of all these categories:
Sub-Category
Single Color - Axial - Gull Wing LED
Single Color - Top Emitting LED - 0603
Single Color - Top Emitting LED - 0805
Single Color - Top Emitting LED - 1106
Single Color - Top Emitting LED - 1108
Single Color - Top Emitting LED - 1206
Single Color - Top Emitting - PLCC2
Single Color - Top Emitting - High Brightness LED
Single Color - Side Emitting LED – 0802
Single Color - Side Emitting LED – 1104
Single Color - SOT-23 LED
Single Color - SMD Subminiature LED
The PLCC2 are the normal sized and narrow sized decent to work with. The High Brightness are way too big, and all the othres are ridiculous to work with... Literally grains of salt, you need a magnifying glass and reading glasses to work with them. I don't wear glasses normally, but I borrowed some when I replaced all my headunit's 0603 LEDs with white ones.
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LC-LED calls them "Surface Mount LED - Power Top"
http://lc-led.com/Products/department/5
For white, Pricing Information: 15-99 pcs : $1.35 USD
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Looks like ELED wins by a pretty high margin... Just be careful not to heat the white ones up too much or the phosphor burns and they give off a more greenish hue instead of pure white... other than that, just physically doing it is the only hard part. Buy at least 5 more than you need, you WILL kill or lose a few I guarantee it. Even if you're an expert, They get lost easy.