Please read the following table in HTML format from a webpage and then answer the question in detail according to the table. Each table cell is defined by a <td> and a </td> tag. Each table row starts with a <tr> and ends with a </tr> tag. 'rowspan=m' and 'colspan=n' represents a cell spaning over 'm' rows and 'n' columns.

Webpage title:
Type 63 (tank)
Table title:
Models
Table:
<table id='hittask' contenteditable='False'>
<tr> <th colspan=1 rowspan=1 >  </th><td class="highlighted"  colspan=1 rowspan=1 > Type 63 </td><td colspan=1 rowspan=1 > Type 63-I </td><td colspan=1 rowspan=1 > Type 63-II </td><td colspan=1 rowspan=1 > Type 63A </td><td colspan=1 rowspan=1 > Type 63A-I </td><td colspan=1 rowspan=1 > Type 63A-II </td></tr>
<tr> <th colspan=1 rowspan=1 > Weight (tonnes) </th><td colspan=1 rowspan=1 > 18.4 </td><td colspan=1 rowspan=1 > 19.83 </td><td colspan=1 rowspan=1 > Unknown </td><td colspan=1 rowspan=1 > 22 </td><td colspan=2 rowspan=1 > Unknown </td></tr>
<tr> <th colspan=1 rowspan=1 > Length </th><td colspan=3 rowspan=1 > 8.44 m (overall) 7.15 m (hull only) </td><td colspan=3 rowspan=1 > 9.6 m (overall) </td></tr>
<tr> <th colspan=1 rowspan=1 > Main gun </th><td colspan=3 rowspan=1 > 85 mm Type 62-85TC rifled (47 rounds) </td><td colspan=3 rowspan=1 > 105 mm low recoil rifled (45 rounds) </td></tr>
<tr> <th class="highlighted"  colspan=1 rowspan=1 > Engine </th><td class="highlighted"  colspan=1 rowspan=1 > 6-cylinder 4-stroke in-line water-cooled diesel 241 hp (180 kW) at 1,800 rpm </td><td colspan=2 rowspan=1 > 12150L-2 12-cylinder 4-stroke in-line water-cooled diesel 402 hp (300 kW) at 2,000 rpm </td><td colspan=3 rowspan=1 > Diesel 581 hp (433 kW) </td></tr>
</table>
Question:
How many cylinders was the variant of type 63?
Answer:
The variant of Type 63 was the 6-cylinder 4-stroke inline water-cooled diesel engine developing 241 hp (180 kW) at 1800 rpm.