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Standard H4 (60/55W) is an economical quality replacement for the stock bulb in the early Vanagons. In Europe T3s were also sold with round headlights at a later date and rectangular lights also used H4 bulbs.
The 9003 Vision Plus is also an H4 bulb offering 60% better light according to the manufacturer although we are not sure how the 60% are measured. Their power consumption remains the same as standard bulbs.
H4 Ultra offers a whiter light due to its slight blue color tint and better overall illumination.
The 9004 standard is a straight and economical replacement of your stock outer headlight bulb.
The 9004 Vision Plus bulb is an upgrade worth considering as the stock rectangular headlights do not provide great illumination to start with. It claims to have 60% more light.
If you want a bright whiter light the Xenon/Halogen Crystal Vision Plus 9004CVP replacement bulbs may be for you (please call).
H3 bulbs are used for the small rectangular high beam lights in T3 Vanagon from 86 on.
Note: the higher end bulbs provide more light but their lifespan will often be shorter which results in higher overall cost. We sometimes have alternatives from other brands.